Glutamate receptor compositions and method

ABSTRACT

The present invention discloses novel DNAs that encode proteins having electrophysiological and pharmacological properties characteristic of glutamate receptors. The glutamate receptors are exemplified by proteins encoded by representative cDNA clones GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7, fragments thereof, and functional combinations of these glutamate receptor proteins and/or fragments. DNA sequences from the cDNA clones for GluR1, GluR2, GluR3, GluR4 and GluR5 are especially useful as probes, thus enabling those skilled in the art to identify, without undue experimentation, other members of the L-glutamate receptor family.

ACKNOWLEDGEMENT

This invention was made with Government support under Grant Numbers NS 11549 and NS 28709.01, awarded by the National Institutes of Health. The Government has certain rights in this invention.

PRIOR APPLICATIONS

This application is a divisional application of U.S. Ser. No. 08/013,767, filed Feb. 4, 1993, now abandoned which is a divisional of U.S. Ser. No. 07/718,575, filed Jun. 21, 1991, now U.S. Pat. No. 5,202,257, which is a continuation of PCT Application No. US90/06153, filed Oct. 25, 1990, which is a continuation-in-part application of U.S. Ser. No. 07/428,116, filed October 27, 1989, now abandoned.

FIELD OF THE INVENTION

The present invention relates to a family of novel DNA sequences and receptor proteins encoded thereby that comprise the glutamate neurotransmitter system. The invention also relates to methods for making such glutamate receptors and for using the receptor proteins in assays designed to identify and characterize compounds which affect the function of such receptor s, e.g., glutamate agonists and antagonists.

BACKGROUND OF THE INVENTION

The amino acid L-glutamate is a major excitatory neurotransmitter in the mammalian central nervous system. Anatomical, biochemical and electrophysiological analyses suggest that glutamatergic systems are involved in a broad array of neuronal processes, including fast excitatory synaptic transmission, regulation of neurotransmitter releases, long-term potentiation, learning and memory, developmental synaptic plasticity, hypoxic-ischemic damage and neuronal cell death, epileptiform seizures, as well as the pathogenesis of several neurodegenerative disorders. See generally, Monaghan et al., Ann. Rev. Pharmacol. Toxicol. 29:365-402 (1980). This extensive repertoire of functions, especially those related to learning, neurotoxicity and neuropathology, has stimulated recent attempts to describe and define the mechanisms through which glutamate exerts its effects.

Currently, glutamate receptor classification schemes are based on pharmacological criteria which serve to define five receptor subtypes or classes: those activated by N-methyl-D-aspartic acid (NMDA), kainic acid (KA), α-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA, formally called the quisqualic acid or QUIS receptor), 2-amino-4-phosphonobutyric acid (AP4 or APB), and 1-amino-cyclopentyl-1,3-dicarboxylic acid (ACPD). The effects of glutamate are mediated primarily through interactions with cation-selective, ionotropic receptors Foster and Fagg, Brain Res. 7:103-164 (1984); Strange, Biochem. J. 249:309-318 (1988)!. An exception is the ACPD receptor subtype which has the properties of a metabotropic receptor. This class of glutamate receptors alters synaptic physiology via GTP-binding proteins and the second messengers diacylglycerol and inositol 1,4,5-triphosphate Gundersen et al., Proc. R. Soc. London Ser. 221:127 (1984); Sladeczek et al., Nature 317:717 (1985); Nicoletti et al., J. Neurosci. 6:1905 (1986); Sugiyama et al., Nature 325:531 (1987)!.

The electrophysiological and pharmacological properties of the glutamate receptors have been extensively studied and are now well established. See, for example, Foster and Fagg, Brain Res. Rev. 7:103 (1984); Cotman et al., Trends Neurosci. 10:263 (1987); Mayer and Westbrook, Prog. Neurobiol. 28:197 (1987); Watkins and Olvermann, Trends Neurosci. 10:265 (1987); and Blair et al., Science 242:577 (1988). This is in contrast to their biochemical characteristics and structure at the molecular level, which, until the teaching of the present invention, remained largely unknown.

SUMMARY OF THE INVENTION

The present invention discloses a family of novel glutamate receptor proteins and DNA sequences that encode them. The glutamate receptors of the invention have electrophysiological and pharmacological properties characteristic of glutamate receptors of the central and peripheral nervous system. The glutamate receptors of the present invention are exemplified by cation-selective ion channel-type proteins encoded by cDNA clones, GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7. In addition to being useful for the production of glutamate receptor proteins, these CDNAS are also useful as probes, thus enabling those skilled in the art, without undue experimentation, to identify and isolate additional proteins in the glutamate receptor family.

The novel functional glutamate receptors of the present invention can be assembled from a plurality of either individual GluR subunit proteins (homomeric) or from combinations of subunit proteins (heteromeric). GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7 are examples of presently preferred subunit proteins for forming homomeric receptors, while the combinations of GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7 are examples of presently preferred subunit proteins for forming heteromeric receptors.

In addition to disclosing novel glutamate receptor proteins, the present invention also comprises methods for using such receptors to identify and characterize compounds which affect the function of such receptors, e.g., agonists, antagonists, and modulators of glutamate receptor function. The invention also comprises methods for determining whether unknown protein(s) are functional as glutamate receptors.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 (a and b) comprises two sequence homology analyses. FIG. 1a compares the extracellular region located between amino acid residues 89 and 106 of GluR1 with the "Cys-Cys-loop" region found in all other ligand-gated ion channels, showing sequence homology. FIG. 1b compares the putative TMD II region of GluR1 with hypothetical TMD II regions of other ligand-gated ion channels, suggesting protein sequence conservation.

FIG. 2A is a drawing which shows the alignment of deduced amino acid sequences for the GluR1, GluR2, GluR3, GluR4 and GluR5 (GluR5-1) subunits of the glutamate receptor gene family.

FIG. 2B is a drawing which shows the alignment of deduced amino acid signal sequences for the GluR1, GluR2, GluR3, GluR4, GluR5 (GluR5-1), GluR6 and GluR7 subunits of the glutamate receptor gene family.

FIG. 3 (A and B) is comprised of two graphs which compare current responses measured in Xenopus) oocytes injected with individual GluR1, GluR2 and GluR3 subunit RNAs (FIG. 3A) or rat brain hippocampus poly(A)⁺ RNA (FIG. 3B).

FIG. 4 (A and B) is comprised of two graphs which compare current responses measured in Xenopus oocytes injected with combinations of GluR1, GlUR2 and GluR3 RNAs.

FIG. 5 is comprised of three graphs which illustrate the dependence of the current responses to 100 mM KA upon the membrane potential.

FIG. 6 presents an alignment of the deduced amino acid sequences of the rat glutamate receptor subunits GluR1, GluR5 and GluR6. The GluR5 clone GluR5-1 (without a 15 amino acid insert) is used for the alignment see Bettler et al., Neuron 5: 583-595 (1990)!. Positions with amino acids identical between at least two proteins are enclosed and shaded. The predicted signal peptide and membrane spanning regions (MSR) are indicated see Devereux et al., Nucl. Acids Res. 12: 387-395 (1984)!. Numbers indicate positions in the mature subunits.

FIG. 7a presents dose response curves obtained on GluR6 injected oocytes.

FIG. 7b presents the current-voltage relationship of the homomeric GluR6 receptor evoked by 10 μM kainate before and after Con A treatment. The asterisk indicates the I/V relationship obtained on Con A treated oocytes in a modified frog Ringer solution in which the NaCl was substituted with an equimolar concentration of sodium methanesulfonate. The currents were normalized to the individual currents measured at -70 mV (30 nA and 2.3 μa in Ringer solution before and after Con A treatment, respectively, and 330 nA in the modified Ringer solution).

The amino acids appearing herein may be identified according to the following three-letter or one-letter abbreviations:

    ______________________________________                                                        3 Letter  1 Letter                                              Amino Acid     Abbreviation                                                                             Abbreviation                                          ______________________________________                                         L-Alanine      Ala       A                                                     L-Arginine     Arg       R                                                     L-Asparagine   Asn       N                                                     L-Aspartic Acid                                                                               Asp       D                                                     L-Cysteine     Cys       C                                                     L-Glutamine    Gln       Q                                                     L-Glutamic Acid                                                                               Glu       E                                                     L-Glycine      Gly       G                                                     L-Histidine    His       H                                                     L-Isoleucine   Ile       I                                                     L-Leucine      Leu       L                                                     L-Lysine       Lys       K                                                     L-methionine   Met       M                                                     L-Phenylalanine                                                                               Phe       F                                                     L-Proline      Pro       P                                                     L-Serine       Ser       S                                                     L-Threonine    Thr       T                                                     L-Tryptophan   Trp       W                                                     L-Tyrosine     Tyr       Y                                                     L-Valine       Val       V                                                     ______________________________________                                    

The nucleotides appearing herein have the usual single-letter designations (A, G, T, C or U) routinely used in the art.

DETAILED DESCRIPTION OF THE INVENTION

The present invention discloses a family of glutamate receptors, novel DNA sequences that encode these receptors, and various applications thereof.

As used herein, glutamate receptors refer to neurotransmitter receptor proteins that are activated by L-glutamate and related compounds. These receptor proteins are classified on the basis of their "pharmacology". Currently there are five classes of receptors, i.e., receptors activated by (1) N-methyl-D-aspartate (NMDA), which is a ligand (agonist) for the NMDA glutamate receptor subtype; (2) kainic acid (KA), which is a ligand (agonist) for the kainate glutamate receptor subtype; (3) a-amino-3-hydroxy-5-methyl-isoxazole-4-propionic acid (AMPA), which is a ligand (agonist) for the AMPA glutamate receptor subtype, formerly called the quisqualic acid or QUIS receptor, wherein QUIS means quisqualic acid or quisqualate, which is a ligand (agonist) for the pharmacologically defined receptor subtype previously referred to as the QUIS (quisqualate) receptor; (4) 2-amino-4-phosphonobutyric acid (AP4 or APB), which is a ligand (agonist) for the APB glutamate receptor subtype; the acronym AP4 is also used to refer to this receptor subtype; and (5) 1-aminocyclopentyl-1,3-dicarboxylic acid (ACPD), which is a ligand (agonist) for the ACPD glutamate receptor subtype.

The effects of glutamate on the first four subtypes described above are mediated primarily through interactions with cation-selective, ionotropic receptors. The ACPD receptor subtype, however, is an exception in that it has the properties of a metabotropic receptor. Metabotropic receptors alter synaptic physiology via GTP-binding proteins and second messengers (i.e., diacylglycerol and inositol 1,4,5-triphosphate).

In one aspect, the present invention comprises substantially pure proteins, or functional fragments thereof, having electrophysiological and pharmacological properties characteristic of at least one ionotropic glutamate receptor subtype selected from the N-methyl-D-aspartate (NMDA) subtype, the α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) subtype, kainate (KA) subtype or the 2-amino-4-phosphonobutyrate (APB) subtype.

When used herein as a modifier of glutamate receptor protein(s) of the present invention, the phrase "having electrophysiological and pharmacological properties characteristic of a glutamate receptor" means that the neuronal signal(s) generated by receptor protein in response to glutamate or glutamate-like ligands will be comparable to those of known glutamate receptors.

The term "functional", when used herein as a modifier of glutamate receptor protein(s) of the present invention (or fragments thereof), means that binding of glutamate (or glutamate-like) ligand to receptor protein(s) causes membrane "ion channels" to open. This allows ions to move across the membrane, which in turn depolarizes the cell and generates a neuronal signal. Stated another way, "functional" means that a neuronal signal is generated as a consequence of ligand binding to receptor protein(s).

As used herein, the words "protein", "peptide" and "polypeptide" are considered to be equivalent terms and are used interchangeably.

Also contemplated by the present invention are homomeric and heteromeric (or multimeric) combinations of the above-described receptor subtypes.

As used herein, homomeric means receptors comprised of a plurality of only one type of subunit protein, e.g., homodimers, homotrimers, etc.

As used herein, heteromeric or multimeric means receptors comprised of more than one type of subunit protein.

In another aspect, the invention comprises antibodies generated against the above-described receptor proteins. Such antibodies can be used to modulate the ion channel activity of glutamate receptors, by contacting such receptors with an effective amount of such antibody.

In yet another aspect, the invention comprises substantially pure DNA encoding proteins or functional fragments thereof, as described hereinabove.

Use of the phrase "substantially pure" in the present specification and claims as a modifier of DNA, RNA, polypeptides or proteins means that the DNA, RNA, polypeptides or proteins so designated have been separated from their in vivo cellular environment. As a result of this separation and purification, the substantially pure DNAs, RNAs, polypeptides and proteins are useful in ways that the non-separated, impure DNAs, RNAs, polypeptides or proteins are not.

In still another aspect, the invention comprises cells transformed with DNAs of the invention.

In another aspect, the invention comprises substantially pure sense or antisense mRNA transcribed from the above-described DNAs, wherein the DNAs encode substantially pure functional proteins that have electrophysiological and pharmacological properties characteristic of a glutamate receptor.

In still another aspect, the invention comprises Xenopus oocytes to which mRNA of the invention has been introduced, e.g., by injection.

Still further, the invention comprises novel glutamate receptors made by expression of DNA sequences of the invention, or translation of the corresponding mRNAs. Such novel receptors include the individual GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7 receptors, fragments thereof, plus functional combinations of the receptors or fragments.

Still further, the invention comprises DNA, RNA and proteins that are functionally equivalent to the DNAs, RNAs and proteins of the present invention. Such functionally equivalent DNAs, RNAs and proteins will function in substantially the same manner as the DNAs, RNAs and proteins of the invention.

Presently preferred proteins of the invention, or functional fragments thereof, or functional combinations of these proteins and/or fragments, are proteins or functional fragments or functional combinations thereof which have electrophysiological and pharmacological properties characteristic of KA and/or AMPA glutamate receptor subtypes.

The invention proteins, or functional fragments thereof, or functional combinations of the proteins and/or the fragments, can be characterized as being encoded by DNA having at least about 40% nucleic acid homology with at least one member of the group consisting of GluR1 DNA (see, for example, Sequence ID No. 1), GluR2 DNA (see, for example, Sequence ID No. 3), GluR3 DNA (see, for example, Sequence ID No. 5), GluR4 DNA (see, for example, Sequence ID No. 7), GluR5 DNA (see, for example, Sequence ID No. 9), GluR6 DNA (see, for example Sequence ID No. 11) and GluR7 DNA (see, for example, Sequence ID No. 13), as well as substantially pure functional proteins having substantial sequence homology with the substantially pure functional proteins of the invention.

The phrase "substantial sequence homology", as used in the present specification and claims, means that the DNA, RNA or amino acid sequences which have slight and non-consequential sequence variations from the actual sequences disclosed and claimed herein are considered to be equivalent to the sequences of the present invention, and as such are within the scope of the appended claims. In this regard, "slight and non-consequential sequence variations" mean that "homologous" sequences (i.e., the sequences that have substantial sequence homology with the DNA, RNA, or proteins disclosed and claimed herein) will be functionally equivalent to the sequences disclosed and claimed in the present invention. Functionally equivalent sequences will function in substantially the same manner to produce substantially the same compositions as the nucleic acid and amino acid compositions disclosed and claimed herein.

Alternatively, the invention proteins, or functional fragments thereof, or functional combinations of the proteins and/or the fragments can be characterized as receptors which have at least about 40% overall amino acid homology with at least one member of the group consisting of GluR1 (see, for example, Sequence ID No. 2), GluR2 (see, for example, Sequence ID No. 4), GluR3 (see, for example, Sequence ID No. 6), GluR4 (see, for example, Sequence ID No. 8), GluR5 (see, for example, Sequence ID No. 10), GluR6 (see, for example, Sequence ID No. 12) and GluR7 (see, for example, Sequence ID No. 14), as well as substantially pure functional proteins having substantial sequence homology with the substantially pure functional proteins of the invention.

Presently preferred receptor proteins of the invention, or functional fragments thereof, or functional combinations of such proteins and/or fragments are characterized as receptors having at least about 50% amino acid homology in the C-terminal domain thereof with the C-terminal domain of at least one member of the group consisting of GluR1 (see, for example, Sequence ID No. 2), GluR2 (see, for example, Sequence ID No. 4), GluR3 (see, for example, Sequence ID No. 6), GluR4 (see, for example, Sequence ID No. 8), GluR5 (see, for example, Sequence ID No. 10), GluR6 (see, for example, Sequence ID No. 12) and GluR7 (see, for example, Sequence ID No. 14), as well as substantially pure functional proteins having substantial sequence homology with the substantially pure functional proteins of the invention.

Exemplary receptors of the invention comprise substantially pure proteins selected from GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7, and combinations thereof wherein said combinations are functional as glutamate receptor(s).

As used herein, GluR1 refers to a cDNA clone which encodes a single glutamate receptor subunit protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 99.8 kilodaltons (kD). GluR1 was the first glutamate receptor subunit encoding cDNA to be isolated; it was previously referred to as GluR-K1. GluR-K1 has been renamed glutamate receptor subunit gene 1 or, more simply, GluR1. Additional glutamate receptor subunits or subunit related genes are called GluR2, GluR3, GluR4, GluR5, GluR6, GluR7 and so forth. GluR1 cDNA was deposited with the American Type Culture Collection on Oct. 19, 1989; and has been accorded ATCC Accession No. 68134.

As used herein GluR2 refers to a cDNA clone which encodes a single glutamate receptor subunit protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 96.4 kD. GluR2 cDNA was deposited with the American Type Culture Collection on Oct. 19, 1989; and has been accorded ATCC Accession No. 68132.

As used herein, GluR3 refers to a cDNA clone which encodes a single glutamate receptor subunit protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 98.0 kD. GluR3 cDNA was deposited with the American Type Culture Collection on Oct. 19, 1989; and has been accorded ATCC Accession No. 68133.

As used herein, GluR4 refers to a cDNA clone which encodes a single protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 98.5 kD. GluR4 cDNA was deposited with the American Type Culture Collection on Aug. 2, 1990; and has been accorded ATCC Accession No. 68375.

As used herein, GluR5 refers to a GluR5 cDNA clone which encodes a single protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 100 kD. GluR5 cDNA (as GluR5-1) was deposited with the American Type Culture Collection on Aug. 2, 1990; and has been accorded ATCC Accession No. 68374. There are two length variants of GluR5 cDNA, referred to herein as GluR5-1 and GluR5-2. Translation of the GluR5 cDNAs predicts a single long open reading frame of 920 amino acids. The difference between GluR5-1 and GluR5-2 DNA derives from an insertion of 45 nucleotides (15 amino acids) in the GluR5-1 DNA which does not interrupt this reading frame. The 15 amino acid insertion in the GluR5-1 receptor protein is unique among the receptor proteins disclosed herein; thus the shorter GluR5-2 variant is the counterpart of the GluR1, GluR2, GluR3, GluR4, GluR6 and GluR7 subunits.

As used herein, GluR6 refers to a cDNA clone which encodes a single protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 100 kD.

As used herein, GluR7 refers to a cDNA clone which encodes a single protein of the same name having a M_(r) (of the non-glycosylated receptor) of approximately 100 kD.

As used herein, GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7 are each used interchangeably to refer to genes, cDNA clones and the glutamate receptor proteins they encode.

Presently preferred receptors of the invention comprise substantially pure proteins having M_(r) s (of the non-glycosylated receptor) of about 99.8 kD (GluR1), 96.4 kD (GluR2), 98.0 kD (GluR3), 98.5 kD (GluR4), 100 kD (GluR5), 100 kD (GluR6), and 100 kD (GluR7), as well as channels which possess the electrophysiological and pharmacological properties characteristic of glutamate receptors of the KA and/or AMPA subtypes.

In accordance with yet another embodiment of the present invention, there are provided antibodies generated against the above-described receptor proteins. Such antibodies can be employed for diagnostic applications, therapeutic applications, and the like. Preferably, for therapeutic applications, the antibodies employed will be monoclonal antibodies.

The above-described antibodies can be prepared employing standard techniques, as are well known to those of skill in the art, using the invention receptor proteins as antigens for antibody production.

In accordance with still another embodiment of the present invention, there are provided methods for modulating the ion channel activity of receptor(s) of the invention by contacting said receptor(s) with an effective amount of the above-described antibodies.

The antibodies of the invention can be administered to a subject employing standard methods, such as, for example, by intraperitoneal, intramuscular, intravenous, or subcutaneous injection, implant or transdermal modes of administration, and the like. One of skill in the art can readily determine dose forms, treatment regiments, etc, depending on the mode of administration employed.

The invention DNA can be characterized as comprising substantially pure DNA having at least about 50% overall nucleic acid homology with at least one member of the group consisting of GluR1 DNA, GluR2 DNA, GluR3 DNA, GluR4 DNA, GluR5 DNA, GluR6 DNA and GluR7 DNA.

Alternatively, the invention DNA comprises substantially pure DNA encoding proteins having at least about 40% overall amino acid homology with at least one member of the group consisting of GluR1 (see, for example, Sequence ID No. 2), GluR2 (See, for example, Sequence ID No. 4), GluR3 (see, for example, Sequence ID No. 6) GluR4 (see, for example, Sequence ID No. 8), GluR5 (see, for example, Sequence ID No. 10), GluR6 (see, for example, Sequence ID No. 12), and GluR7 (see, for example, Sequence ID No. 14).

Presently preferred DNA are substantially pure DNA encoding substantially pure proteins having M_(r) s (of the non-glycosylated receptor) of about 99.8 kD (GluR1), 96.4 kD (GluR2), 98.0 kD (GluR3), 98.5 kD (GluR4), 100 kD (GluR5), 100 kD (GluR6), and 100 kD (GluR7), as well as combinations thereof that form ion channels which possess the electrophysiological and pharmacological properties characteristic of a glutamate receptor of the KA and/or AMPA subtypes.

Especially preferred DNA sequences of the invention comprise substantially pure DNA selected from GluR1 DNA (see, for example, Sequence ID No. 1), GluR2 DNA (see, for example, Sequence ID No. 3), GluR3 DNA (see, for example, Sequence ID No. 5), GluR4 DNA (see, for example, Sequence ID No. 7), GluR5 DNA (see, for example, Sequence ID No. 9), GluR6 DNA (see, for example, Sequence ID No. 11) and GluR7 DNA (see, for example, Sequence ID No. 13).

Also contemplated by the present invention are substantially pure DNA that are functionally equivalent to any of the substantially pure DNAs of the invention, wherein functionally equivalent means that the substantially pure DNA will encode proteins, or functional fragments thereof, which will form ion channel(s) in response to ligands for glutamate receptors.

Representative clones of the above-described DNA sequences have been deposited with the American Type Culture Collection. The representative cDNA clones include: GluR1 (ATCC No. 68134), GluR2 (ATCC No. 68132), GluR3 (ATCC No. 68133), GluR4 (ATCC No. 68375), and GluR5 (ATCC No. 65374).

Either the full length cDNA clones or fragments thereof can be used as probes, preferably labeled with suitable label means for ready detection. When fragments are used as probes, preferably the DNA sequences will be from the carboxyl encoding portion of the DNA, and most preferably will include ion channel encoding portions of the DNA sequence. These probes can be used, for example, for the identification and isolation of additional members of the glutamate receptor family.

In another aspect, the invention comprises functional peptide fragments, and functional combinations thereof, encoded by the DNAs of the invention. Such functional peptide fragments can be produced by those skilled in the art, without undue experimentation, by eliminating some or all of the amino acids in the sequence not essential for the peptide to function as a glutamate receptor. A determination of the amino acids that are essential for glutamate receptor function is made, for example, by systematic digestion of the DNAs encoding the peptides and/or by the introduction of deletions into the DNAs. The modified (e.g., deleted or digested) DNAs are expressed, for example, by transcribing the DNA and then introducing the resulting mRNA into Xenopus oocytes, where translation of the mRNAs will occur. Functional analysis of the proteins thus expressed in the oocytes is accomplished by exposing the oocytes to ligands known to bind to and functionally activate glutamate receptors, and then monitoring the oocytes to see if the expressed fragments form ion channel(s). If ion channel(s) are detected, the fragments are functional as glutamate receptors.

In addition to DNA, RNA and protein compositions of matter, several novel methods are contemplated by the present invention. The first is a method for identifying DNA that is homologous to DNA known to encode glutamate receptor protein(s). This method comprises contacting an "unknown" or test sample of DNA with a glutamate receptor DNA probe (e.g., GluR1, GluR2, GluR3, GluR4, GluR5, GluR6, GluR7, etc.) under suitable hybridization conditions, and then identifying "unknown" or test DNA which hybridizes with the glutamate probe DNA as glutamate receptor homologous DNA.

Such screening is initially carried out under low-stringency conditions, which comprise a temperature of about 37° C. or less, a formamide concentration of less than about 50%, and a moderate to low salt (SSC) concentration; or, alternatively, a temperature of about 50° C. or less, and a moderate to high salt (SSPE) concentration. Presently preferred conditions for such screening comprise a temperature of about 37° C., a formamide concentration of about 20%, and a salt concentration of about 5×standard saline citrate (SSC; 20×SSC contains 3M sodium chloride, 0.3M sodium citrate, pH 7.0); or a temperature of about 50° C., and a salt concentration of about 2×SSPE (1×SSPE contains 180 mM NaCl, 9 mM Na₂ HPO₄, 0.9 mM NaH₂ PO₄ and 1 mM EDTA, pH 7.4). Such conditions will allow the identification of sequences which have a substantial degree of similarity with the probe sequence, without requiring perfect homology for the identification of a stable hybrid. The phrase "substantial similarity" refers to sequences which share at least 50% overall sequence identity. Preferably, hybridization conditions will be selected which allow the identification of sequences having at least 70% sequence identity with the probe, while discriminating against sequences which have a lower level of sequence identity with respect to the probe.

After low stringency hybridization has been used to identify several clones having a substantial degree of similarity with the probe sequence, this subset of clones is then subjected to high stringency hybridization, so as to identify those clones having particularly high level of homology with respect to the probe sequences. High stringency conditions comprise a temperature of about 42° C. or less, a formamide concentration of less than about 20%, and a low salt (SSC) concentration; or, alternatively, a temperature of about 65° C. or less, and a low salt (SSPE) concentration. Presently preferred conditions for such screening comprise a temperature of about 42° C., a formamide concentration of about 20%, and a salt concentration of about 2×SSC; or a temperature of about 65° C., and a salt concentration of about 0.2×SSPE.

Another method of the invention is directed to identifying functional glutamate receptors (i.e., glutamate receptors that form ion channels). This method comprises contacting glutamate receptor proteins, preferably in an oocyte expression system, with at least one ligand known to activate such receptors, measuring ion channel response to the ligand(s), and identifying as functional glutamate receptor(s) those proteins which exhibit an ion channel response as a consequence of the contact.

In accordance with a further embodiment of the present invention, there is provided a binding assay employing receptors of the invention, whereby a large number of compounds can be rapidly screened to determine which compounds, if any, are capable of binding to glutamate receptors. Subsequently, more detailed assays can be carried out with those compounds found to bind, to further determine whether such compounds act as modulators, agonists or antagonists of invention receptors.

Another application of the binding assay of the invention is the assay of test samples (e.g., biological fluids) for the presence or absence of receptors of the present invention. Thus, for example, serum from a patient displaying symptoms related to glutamate pathway dysfunction can be assayed to determine if the observed symptoms are perhaps caused by over- or under-production of such receptor(s).

The binding assays contemplated by the present invention can be carried out in a variety of ways, as can readily be identified by one of skill in the art. For example, competitive binding assays can be employed, as well as radioimmunoassays, ELISA, ERMA, and the like.

Yet another method of the invention involves determining whether a substance is a functional ligand for glutamate receptor protein (i.e., a modulator, an agonist or an antagonist of glutamate receptor(s)). According to this method, proteins known to function as glutamate receptors are contacted with an "unknown" or test substance (in the further presence of a known glutamate agonist, when antagonist activity is being tested), the ion channel activity of the known glutamate receptor is monitored subsequent to the contact with the "unknown" or test substance, and those substances which increase or decrease the ion channel response of the known glutamate receptor(s) are identified as functional ligands (i.e., modulators, agonists or antagonists) for receptor proteins.

As yet another application of the invention sequences, genetic screening can be carried out using the nucleotide sequences of the invention as probes. Thus, patients having neuropathological conditions suspected of involving alteration/modification of any one or more of the glutamate receptors can be screened with appropriate probes to determine if any abnormalities exist with respect to any of the endogenous glutamate receptors. Similarly, patients having a family history of disease states related to glutamate receptor dysfunction can be screened to determine if they are also predisposed to such disease states.

Turning now to some of the specific DNAs of the invention, cDNA clone GluR1 was isolated from a rat forebrain cDNA library by screening for expression of kainate-gated ion channels in Xenonus oocytes. An insert from clone GluR1 was used as a probe to screen cDNA brain libraries (first under low-stringency hybridization conditions and then under higher stringency conditions) in order to find cDNA clones that encode other members of the glutamate receptor family. Use of the GluR1 probe cDNA led to the identification and isolation of the GluR2 and GluR3 clones. A probe from GluR2 was used to identify and isolate clones GluR4 and GluR5, and GluR5 was used to isolate clones for GluR6 and GluR7.

cDNA clone GluR1 encodes a functional glutamate receptor subunit which consists of a single protein having a M_(r) (of the non-glycosylated receptor) of about 99.8 kD, before any post-translational modifications. This protein forms an ion channel which possesses the electrophysiological and pharmacological properties of KA and AMPA receptors.

The proteins encoded by the GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7 genes exhibit considerable inter-subunit amino acid sequence identity, as summarized in Table 1.

                  TABLE 1                                                          ______________________________________                                         The Percent Amino Acid Sequence Identity Among                                 Pairwise Combination of Members of the                                         Glutamate Receptor Subunit Gene Family                                         Glu-                                                                           R1       GluR2   GluR3   GluR4 GluR5 GluR6 GluR7                               ______________________________________                                         A. N-terminal domain                                                           GluR1 100    58      57    55    34    33    33                                GluR2        100     62    62    33    33    33                                GluR3                100   64    34    34    32                                GluR4                      100   32    31    31                                GluR5                            100   75    70                                GluR6                                  100   77                                GluR7                                        100                               B. C-terminal domain                                                           GluR1 100    86      84    84    49    51    48                                GluR2        100     89    88    49    51    50                                GluR3                100   87    51    54    50                                GluR4                      100   51    52    48                                GluR5                            100   89    79                                GluR6                                  100   87                                GluR7                                        100                               C. Overall amino acid sequence identity                                        GluR1 100    70      69    68    40    41    39                                GluR2        100     73    72    40    41    40                                GluR3                100   73    41    42    40                                GluR4                      100   41    40    39                                GluR5                            100   80    78                                GluR6                                  100   79                                GluR7                                        100                               ______________________________________                                          The sequences were compared using sequence analysis software from the          University of Wisconsin Genetics Computer Group  Devereux et al., Nucl.        Acids Res. 12:387 (1984)!. The percent sequence identity between paired        sequences was calculated by dividing the number of aligned positions with      identical amino acids by the total number of aligned positions in the          shortest of the sequences examined and multiplying the quotient by 100.  

These proteins have been found to form distinct homomeric and heteromeric KA/AMPA-sensitive ion channels in Xenopus oocytes. For example, single protein subunits of glutamate receptors, GluR1, GluR2, GluR3, GluR4 and GluR5 are sufficient to form homomeric functional receptor ion-channel complexes activated by KA, AMPA, and QUIS but not by NMDA and APB. While GluR2 subunits can form functional homomeric complexes, this subunit more efficiently assembles receptor-ion channel complexes in heteromeric combination with GluR1 or GluR3 subunits. GluR6 forms homomeric ion channels which are responsive to KA, but not to AMPA.

The GluR5 protein in Xenopus oocytes forms a homomeric ion channel which is weakly responsive to glutamate but not to N-methyl-D-aspartate, kainate, quisqualate and 2-amino-4-phosphonobutyrate. The fact that oocytes expressing GluR5 are responsive to L-glutamate but not to KA, quisqualate or AMPA indicates that this protein can participate in the formation of receptors with a different pharmacological profile than the KA/AMPA subunits.

During embryonic and postnatal development the GluR5 gene is expressed in subsets of neuronal cells in the central nervous system (CNS) and the peripheral nervous system (PNS). The spatial and temporal expression pattern of the GluR5 gene is largely overlapping with the KA/AMPA subunit GluR4. However, in adult brains, the GluR5 gene is expressed in a pattern distinct from those of the KA/AMPA subunit genes, consistent with GluR5 being a subtype of glutamate receptors different from the KA/AMPA receptors.

DEPOSITS

cDNA clones encoding representative glutamate receptor protein subunits of the present invention have been deposited with the American Type Culture Collection, Rockville, Md., U.S.A. (ATCC). The deposits have been made under the terms of the Budapest Treaty on the International Recognition of Deposits of Microorganisms for Purposes of Patent Procedure and the Regulations promulgated under this Treaty. Samples of the cloned DNA sequences are and will be available to industrial property offices and other persons legally entitled to receive them under the terms of the Treaty and Regulations and otherwise in compliance with the patent laws and regulations of the United States of America and all other nations or international organizations in which this application, or an application claiming priority of this application, is filed or in which any patent granted on any such application is granted.

Without further elaboration, one of ordinary skill in the art can, using the preceding description, and the following Examples, utilize the present invention to its fullest extent. The material disclosed in the examples is disclosed for illustrative purposes and therefore should not be construed as being limiting in any way of the appended claims.

EXAMPLES

As used herein, bp means base pairs. Kbp means kilobase pairs, or 1000 base pairs.

As used herein, all temperatures are given in degrees Centigrade unless indicated otherwise.

Example I Production of Brain cDNA Libraries

Poly(A)⁺ RNA from various regions of the brain, e.g., mammalian brain, or a suitable cell line, e.g., the NCB-20 cell line, is purified by the guanidine thiocyanate-CsCl method Chirgwin et al., Biochem 18:5294 (1979)!. The purified RNA is used as a template to prepare double strand cDNA. A poly-dT primer linked to a XhoI restriction site is used as a primer to prime the Moloney reverse transcriptase for the synthesis of the first strand using 5-methyl dCTP instead of CCTP as a precursor. RNaseH and DNA polymerase I are added to complete the second strand. The cDNA is blunt-ended with T4 DNA polymerase which increases the chance of making a full-length cDNA. EcoRI adapters are ligated to the blunt-end and the ends are kinased. The cDNA is then digested with the restriction enzyme, XhoI. This enzyme only cleaves the un-methylated XhoI restriction site attached to the dT-primer at the 3' end of the mRNA. The resulting double stranded cDNA has a XhoI restriction site at the 3' end of the mRNA and an EcoRI site at the 5' end. This cDNA is then placed into an appropriate vector, such as λZAP vector, which is part of the λZAP-cDNA cloning system from Stratagene. When the λZAP vector is used, the cDNA is placed into the vector so that the 5' end of the mRNA is near the lacZ promoter. The λZAP vector has a T3 RNA polymerase promoter at one end of the cDNA insert and a T7 RNA polymerase promoter at the other end which makes it possible to synthesize either sense or antisense RNA for further experiments, including expression in oocytes.

Example II Low and High Stringency Hybridization

cDNA libraries are preferably made with the λZAP-cDNA system described in Example I. A hybridization probe is preferably made from DNA obtained from GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 or GluR7 clones or another suitable clone or source. The DNA is labeled by the random prime method, preferably using the Amersham Multiprime DNA labeling kit (Amersham Corporation, Chicago, Ill.). Preferably, low stringency hybridization conditions are used, at least at first. A suitable hybridization solution is as follows:

1 M NaCl, 50 mM Tris pH 8.0!,

0.5% SDS, 0.1% sodium pyrophosphate,

100 mg/ml denatured herring sperm DNA, 0.1% w/v! each of Ficoll,

polyvinylpyrrolidone and bovine serum albumin.

For low stringency screening, a temperature of 50° C. is preferable, and library filters are washed in 2×SSPE (wherein 1×SSPE is 180 mM NaCl, 9 mM Na₂ HPO₄, 0.9 mM NaH₂ PO₄ and 1 mM EDTA, pH 7.4) at room temperature and exposed to Kodak XAR-5 film at -70° C.

Under these low-stringency hybridization conditions, about one in two thousand brain cDNA clones show some hybridization to the probe made from the glutamate receptor cDNA insert.

For high stringency screening, the temperature is adjusted to 65° C. and the filters are washed at this temperature in 0.2×SSPE containing 0.5% sodium dodecyl sulfate. Filters are exposed to Kodak XAR-5 film with Cronex Quanta II/III intensifying screens at -70° C. for 18-48 hours.

Example III Analysis of Clones Identified by Hybridization

At least two different approaches can be used to analyze clones that are identified by low-stringency hybridization screening. One approach is to pick positive λZAP clones and pool them into mixtures of about 100 clones. mRNA is made in vitro from these pools of λZAP clones and the mRNA is injected into oocytes in order to test the ability of the mRNA to direct synthesis of functional glutamate receptors. If a positive clone is found, the individual λZAP cDNA clone is isolated by subdividing the pool until the functional clone is isolated. (See Example V, below, for a discussion of how this approach was used to isolate the GluR1 clone.)

A second approach that can be used to evaluate positive clones is to analyze each insert individually. Although this is tedious, the "individual clone" approach has the advantage that initially it does not require functional expression. When the "individual clone" approach is used, each clone is plaque purified and the cDNA insert is analyzed individually. This is facilitated by the fact that, at least in the λZAP cDNA system, the cDNA is cloned into a cassette flanked by the bacteriophage f1 origin of replication. The cDNA is contained within a pBluescript plasmid which can be rescued from the λZAP bacteriophage by helper infection. Once this is done, the cDNA is in the small pBluescript plasmid (which is much easier to work with than the much larger λ-bacteriophage). Sense or antisense RNA is made from the cDNA insert in the pBluescript plasmid using either the T3 (sense) or T7 (anti-sense) promoter.

cDNA inserts can also be analyzed by mapping with restriction enzymes. For example, the cDNA inserts are cut with frequent cutting restriction enzymes, and the resulting fragments size fractionated on a gel. Subsequently, the fragments are transferred to a filter for Southern blot analysis. The filters are hybridized with a probe made from DNA encoding known glutamate receptor subunits, e.g., GluR1, GluR2, GluR3, GluR5, GluR5, GluR6 or GluR7. The hybridizing fragments from each clone are subcloned into the single-stranded vector M13 (mp18 or mp19), and the fragments sequenced. DNA sequencing is performed using standard techniques, such as the dideoxynucleotide chain termination method of Sanger et al. Proc. Natl. Acad. Sci. USA 74:5463 (1977), or an automatic sequencer such as one manufactured by Applied Biosystems. The sequence is preferably analyzed by computer using software such as the programs developed by Intelligenetics, Staden and the University of Wisconsin.

mRNA made from full-length or nearly full-length clones are expressed in the oocyte system and the functional properties of the new receptors are characterized. If a clone is not functional when expressed by itself, it is tested in the presence of mRNA made from other candidate clones.

Example IV Expression Cloning and Assay in XenoPus Oocytes

This assay is an adaptation of the assay of Masu et al., Nature 329:836 (1987). It depends upon the fact that when foreign mRNA is injected into Xenopus oocytes, the mRNA is translated into functional protein.

Either a λZAP cDNA preparation, or a plasmid containing the cDNA to be tested, are cut downstream from the cDNA insert with a restriction enzyme. The post-restriction digest is digested with Proteinase K and then extracted with two phenol: chloroform (1:1) extractions. The resulting DNA fragments are then ethanol precipitated. The precipitated fragments are mixed with either T3 RNA polymerase (to make sense strand), or T7 RNA polymerase (to make anti-sense strand), plus rATP, rCTP, rGTP, rUTP, and RNase inhibitor. Simultaneously, the RNA transcripts are capped with a sodium diguanosine triphosphate G(5')ppp(5')G! cap. The water used for the above procedures is treated with diethylpyrocarbonate to inactivate RNases.

The in vitro synthesized mRNA transcripts are injected into Xenopus oocytes. 50 nl of an RNA solution, 0.2-0.6 mg/ml, is injected into the stage V oocytes. The injected oocytes are incubated at 16° C. in Barth's medium for 2-7 days before they are analyzed for the presence of functional receptors.

Voltage recordings are made by penetrating the oocyte with a micro-electrode filled with 3M KCl and connected to the bridge circuit of an appropriate voltage clamp unit, e.g., the Dagan 8500 voltage clamp unit. Voltage recordings are preferably obtained with two electrodes, a voltage electrode filled with 3M KCl and a current electrode filled with 0.25 M CsCl, 0.25 M CsF and 50 mM EGTA (ethylene glycol tetraacetic acid). Example VI provides a discussion of results of recordings from oocytes injected with RNA from GluR1 cDNA encoding a KA/AMPA glutamate receptor.

Oocytes employed herein are obtained from ovarian tissue from anesthetized adult female Xenopus. The ovarian tissue is treated with collagenase, 2 mg/ml, for two hours and then the ovarian epithelium and follicular cells are dissected away.

Example V Expression Cloning of the GluR1 Receptor

Xenopus oocytes were injected with poly(A)⁺ RNA isolated from rat forebrain. 2-10 days later, the oocytes were tested electrophysiologically for their ability to respond to selective agonists for glutamate receptor subtypes. Both glutamate and quisqualate induce membrane depolarizations. These responses display a biphasic pattern composed of a fast acting, smooth (presumably ligand-gated ion channel) response, and a longer lasting, fluctuating, (probably second-messenger mediated) response. NMDA and KA elicited smooth responses with fast onsets, while APB gave no response.

A directional cDNA library (λZAPII RTB1; complexity: 8×10⁵ elements), consisting of 18 independent sublibraries of 44,000 clones each, was constructed from this poly(A)⁺ RNA using the bacteriophage expression vector λZAPII. A pool of in vitro transcripts, comprised of transcripts made separately from all 18 amplified sublibraries, was injected into oocytes. Small depolarizations (1-3 mV) were seen in voltage recordings from oocytes challenged with 100 μM kainate 10 days after injection. No responses to NMDA or quisqualate were detected. Neither uninjected oocytes nor water-injected oocytes showed any responses to glutamate receptor agonists. Subsequently, pools of 44,000 clones (=the single sublibraries), 4,000, 400 and 40 clones were tested. In each of these tests at least one pool responded to KA.

The following criteria were used throughout the screening procedure to assure that the very small responses observed initially were not recording artifacts: (a) responses in a given oocyte were reproducible, (b) responses were fast (within one second of agonist application), (c) responses were readily reversible upon superfusion of the oocyte with control Ringer solution, (d) 10 μM domoate gave a response similar to the one elicited by 100 μM kainate.

The pools yielding the largest responses at each stage were selected for further subdivision. The clones in the final positive pool of 40 clones were analyzed for their insert size, and the 12 clones with the largest inserts (all>2 kb) were tested individually for their ability to direct the synthesis of a functional kainate receptor. Only one clone, carrying a 3.0 kb insert, was found to elicit kainate responses and was named λZAPII-GluR1.

Example VI Electrophysiological and Pharmacological Characterization of the GluR1 Clone

The plasmid pGluR1 was subsequently rescued from bacteriophage λZAPII-GluR1. Upon transcription and translation in vitro, the translation product of sense RNA (but not antisense RNA) induced kainate responses when injected into oocytes. The GluR1 translation product from as little as 10 pg of GluR1 sense transcript gave detectable responses to 100 μM KA under voltage-clamp conditions (-70 mV holding potential).

In order to rule out the possibility that GluR1 codes for a transcription factor, oocytes injected with pGluR1 in vitro transcripts were kept in medium supplemented with 50 μg/ml actinomycin D to inhibit endogenous transcription. These oocytes exhibited the same responses to kainate as those kept in control medium. Therefore, injection-induced transcription from the oocyte genome does not contribute to the observed responses.

L-glutamate evoked much smaller responses than did KA, and even at 1 mM elicited only 50% of the depolarization seen with 30 μM KA. This is consistent with the observation that glutamate is only a weak agonist for the KA receptor subtype Monaghan et al., Nature 306:176 (1983)!. Other glutamate receptor agonists such as NMDA, quisqualate and L-aspartate evoked no responses when applied at 150 μM, 10 μM, and 100 μM, respectively. Unrelated neurotransmitter receptor agonists such as glycine, γ-aminobutyric acid (GABA_(A)), serotonin and nicotine also failed to evoke responses, even when tested at concentrations as high as 1 mM. Glycine did not potentiate the KA response. Dose-response curves for KA and domoate were recorded and EC₅₀ values of 39 μM and 1.8 μM, respectively, were derived. The average reversal potential was 10 mV, as extrapolated from current responses to 10 μM kainate obtained at a series of holding potentials between 0 and -130 mV. Responses to KA did not desensitize, even after prolonged (up to 10 minutes) superfusion with high concentrations (100 μM) of agonist.

Similarly, the pharmacological profile of GluR1, as revealed by the inhibiting properties of various known glutamate receptor antagonists (see Table 2), is consistent with previous reports for KA receptors in systems where total poly(A)⁺ RNA was used as a source of kainate receptor message Hirono et al., Neurosci. Res. 6:106 (1988); Lerma et al., Proc. Natl. Acad. Sci. USA 86:2083 (1989)!.

As used herein, the term antagonist refers to a substance that interferes with receptor function. Antagonists are of two types: competitive and non-competitive. A competitive antagonist (also known as a competitive blocker) competes with an agonist for overlapping binding sites. A non-competitive antagonist or blocker inactivates the functioning of the receptor by binding to a site on the receptor other than the agonist binding site.

                  TABLE 2                                                          ______________________________________                                         Pharmacology of the Glutamate Receptor Encoded by                              GluR1: Properties of various Glutamate Receptor                                Antagonists as Measured in Oocytes Injected With                               GluR1 in vitro RNA.sup.a                                                                       Compound  Compound Plus                                        Compound        Alone     Kainate                                              Tested.sup.b    (%).sup.c (%).sup.d                                            ______________________________________                                         kainate (agonist control)                                                                      100.0     100.0                                                Kynurenic acid   3.4 ± 0.2                                                                             9.6 ± 1.3                                        γ-DGG      -0.1 ± 0.5                                                                            30.8 ± 1.1                                       GAMS             1.0 ± 0.6                                                                             30.7 ± 1.1                                       GDEE             24.8 ± 5.7                                                                            97.8 ± 6.6                                       PDA              2.5 ± 0.7                                                                             31.3 ± 2.0                                       APV              3.1 ± 1.4                                                                             73.7 ± 3.2                                       CPP              9.1 ± 0.7                                                                             78.8 ± 0.9                                       ______________________________________                                          .sup.a Oocytes had been injected with 1.25 ng of GluR1 in vitro sense RNA      3 days prior to the recording. The oocytes were voltageclamped at -70 mV,      and the test compounds (all at 1 mM, except kainate, which was 30 μM)       applied by rapid superfusion, with 5 minute intervals between drugs. Peak      currents were recorded; each number represents the average of 3 recording      from 3 different oocytes, ± SEM. The 100% current response corresponds      to 40-200 nA, depending on the oocyte.                                         .sup.b = Abbreviations for the compounds used refer to: DGG means              D-glutamylglycine; GAMS means D-glutamylamino-methyl-sulphonate; GDEE          means glutamate diethylester; PDA means 2,3cis-piperidine dicarboxylic         acid; APV means 2amino-5-phospho-novaleric acid; CPP means 3                   (2carboxypiperazin-4-yl)propyl-1-phosphate.                                    .sup.c = % of the response evoked by 30 μM kainate immediately before       drug application.                                                              .sup.d = % of the response seen with 30 μM kainate alone immediately        before application of drug/kainate mixture                               

Of all the compounds tested (each at 1 mM), the road specificity glutamate receptor antagonist kynurenic acid clearly was the most potent inhibitor of the kainate-evoked depolarizations in oocytes injected with GluR1 RNA synthesized in vitro. To a lesser extent, γ-DGG, reported to preferentially block KA and NMDA receptors but not quisqualate receptors Davies and Watkins, Brain Res. 206:173 (1981)!, inhibited kainate responses, as did GAMS, which reportedly prefers KA and AMPA receptors Fagg, Trends Neurosci. 8:207 (1985)!. Similarly, PDA, which is known to block all subtypes of glutamate receptors Foster and Fagg, Brain Res. Rev. 7:103 (1984)!, blocked the GluR1 response. GDEE, which is thought to preferentially inhibit AMPA-type glutamate receptors Foster and Fagg, supra!, did not block the response significantly, but instead displayed weak agonist properties. The NMDA receptor antagonists APV and CPP, as well as NMDA itself, slightly inhibited the KA responses, thus acting as weak antagonists. They did not show any agonist properties.

Taken together, the electrophysiological properties observed in oocytes injected with GluR1 transcript, as well as the observed pharmacological properties, indicate that GluR1 represents a functional KA receptor indistinguishable from the one observed in oocytes injected with total poly(A)⁺ RNA. Thus, the single protein subunit encoded by GluR1 is sufficient to form an active receptor-ion channel complex.

Example VII Sequencing and Primary Structure of GluR1

The cDNA insert of the plasmid pGluR1 was subcloned into M13mp19 and sequenced (see Sequence ID No. 1). An open reading frame of 2721 bp was found within the total length of 2992 bp. The predicted protein consists of 889 amino acids, with a calculated M_(r) (of the non-glycosylated form of the receptor subunit) of about 99.8 kD. The deduced protein sequence contains a putative signal peptide of 18 amino acids at its N-terminus, with a predicted cleavage site that conforms to empirical rules von Heijne, Nucl. Acids Res. 14:4683 (1986)!. The N-terminus of the protein therefore is expected to be located extracellularly. Nucleotides 198 to 251 encode the putative signal peptide, and bases 1 through 197 represent a 5'-untranslated region. At the 3'-terminus of the clone, 71 nucleotides of untranslated sequence were found.

The deduced amino acid sequence for GluR1 is shown in Sequence ID No. 1, along with the nucleotide sequence. The numbering for the amino acid sequence starts with the first residue of the precursor protein, with the first residue of the mature protein being residue 19 (following cleavage of the putative signal sequence). Possible extracellular N-glycosylation sites are present at amino acid residues 63, 249, 257, 363, 401, and 406. The region between amino acids 107-131 bears some resemblance to the ligand-gated ion channel signature postulated by some workers Grenningloh et al., Nature 330:25 (1987); Barnard et al., TINS 10:502 (1987)!. Sequence comparisons with other sequenced ligand-gated ion channels, the nicotinic acetylcholine receptors, GABA_(A) receptors and glycine receptors, reveals little overall homology.

The insert cDNA of the bacteriophage clone λZAPII-GluR-K1 was cut out with EcoRI/XhoI, blunt-ended and subcloned into the SmaI-site of the bacteriophage vector M13mp19 Messing et al., Proc. Natl. Acad. Sci. USA 74:3642 (1977)!, yielding clones with both orientations of the cDNA. Overlapping deleted subclones were constructed for each strand orientation using the Cyclone™ kit from United States Biochemical Corporation (Cleveland, Ohio). Single-stranded sequencing by the dideoxynucleotide chain-termination method Sanger et al., Proc. Natl. Acad. Sci. USA 74:5463 (1977)!, was carried out with all 45 subclones, and additionally, 10 oligonucleotide primers were synthesized to facilitate sequencing across areas where compressions or gaps were encountered in the sequences derived from the deletion subclones. Complete sequences for both strands were thus obtained. IntelliGenetics software packages (IntelliGenetics version 5.0, and PC/Gene™ (IntelliGenetics, Inc., Mountain View, Calif.) were used for analyzing sequences.

All ligand-gated ion channel subunits sequenced prior to the present invention have a conserved extracellular region characterized by 2 cysteine residues spaced 14 amino acids apart from each other, with conserved proline and aspartate residues located 8 and 10 amino acids, respectively, downstream from the first of these two cysteines Barnard et al., Trends Neurosci. 10:502 (1987)!. This hypothetical signature for neurotransmitter receptor-channel complexes is poorly conserved in the protein encoded by GluR1. The proline and aspartate residues are present, but the first cysteine residue is located only 7 residues upstream from the proline residue, and the second cysteine residue is absent.

A hydropathy plot analysis of GluR1 revealed several regions which are candidates for transmembrane domains (TMDs). The region between amino acids 481 and 827 was notable because its hydropathy profile resembled that seen in the other ligand-gated ion channels: three closely spaced putative TMDs which are separated by ˜175 amino acid residues from a fourth putative TMD which is located close to the C-terminus of the protein. Within this region, the following four transmembrane regions are assigned in GluR1: TMD I, located between amino acid residues 481 and 498, TMD II between residues 538 and 556, TMD III between residues 613 and 631, and TMD IV between residues 805 and 825.

FIG. 1a presents a comparison of the extracellular region located between amino acid residues 107 and 124 of GluR1 with the "cys-cys-loop" region found in all other ligand-gated ion channels, showing sequence homology. Sequences of neuronal nicotinic acetylcholine receptor (nAChR) subunits α1, β1, γ, δ are from mouse muscle Heinemann et al., Molecular Neurobiology: Recombinant DNA Approaches (ed. Heinemann, S. & Patrick, J.) 45-96 (Plenum Press, New York, 1987)!, those of nAChR subunits α2, α3, α4, β2, β3, and β4 are from rat brain Deneris et al., J. Biol. Chem. 264:6268 (1989); Duvoisin et al., Neuron 3:487 (1989)!. GABA_(A) subunits α and β are from calf brain Barnard et al., Trends Neurosci 10:502 (1987)!. GlyR 48k is the M_(r) =48 kDa subunit of the glycine receptor from rat brain Grenningloh et al., Nature 328:215-220 (1987)!. Boxed amino acid residues are found at identical positions in GluR1 as well as in at least one of the other receptor sequences. One gap has been introduced arbitrarily.

FIG. 1b presents a comparison of the putative TMD II region of GluR1 with hypothetical TMD II regions of other ligand-gated ion channels Barnard et al., Trends Neurosci. 10:502 (1987); Deneris et al., J. Biol. Chem. 264:6268 (1989); Duvoisin et al., Neuron 3:487 (1989); Grenningloh et al., Nature 328: 215 (1987); Heinemann et al., in: Molecular Neurobiology; Recombinant DNA Approaches (ed. Heinemann, S. & Patrick J.) 45-96 (Plenum Press, New York, (1987)!; suggesting protein sequence conservation.

Example VIII Isolation and Characterization of GluR2 and GluR3

cDNA clones encoding the GluR2 and GluR3 genes were isolated from an adult rat forebrain library using a low-stringency hybridization screening protocol (see Example II) and a radiolabeled fragment of the GluR1 cDNA as probe. Sequence ID Nos. 3 and 5 show the nucleotide and derived amino acid sequences of clones λRB14 (GluR2) and λRB312 (GluR3), respectively. The calculated molecular weights for the mature, non-glycosylated forms of GluR2 and GluR3 are 96,400 daltons (862 amino acids) and 98,000 daltons (866 amino acids), respectively. Potential N-linked glycosylation sites occur in the GluR2 protein at Asn-239, Asn-359, Asn-381, Asn-406, and Asn-851 and in the GluR3 protein at Asn-37, Asn-243, Asn-363, Asn-374, and Asn-394. Like GluR1, the hydrophobicity profile for both GluR2 and GluR3 reveals five strongly hydrophobic regions: one such domain is located at the amino terminus of each protein and has characteristics of a signal peptide, while four additional hydrophobic regions presumably form membrane-spanning regions (MSR I-IV) and are located in the carboxy-terminal domain of each polypeptide.

FIG. 2A is an alignment of the deduced amino acid sequences for the proteins encoded by the GluR1, GluR2, GluR3, GluR4 and GluR5 genes. In the figure, identical residues in all compared sequences are boxed, with spaces introduced as appropriate to maximize homology. Predicted signal peptides and four proposed membrane spanning regions (MSR I-IV) are indicated. The hatched line denotes the insertion of 15 amino acid residues found in the GluR5-1, but not in the GluR5-2 protein. As the aligned sequences demonstrate, there is significant sequence identity between GluR1 and both GluR2 (70%) and GluR3 (69%) as well as between GluR2 and GluR3 (74%; see also Table 1). The sequence identity is most pronounced in the carboxy-terminal half of each protein.

FIG. 2B is a comparison of the deduced amino acid sequences for the signal peptides encoded by the GluR1, GluR2, GluR3, GluR4, GluR5, GluR6 and GluR7 genes.

Example IX Electrophysiological Comparison: GluR1, GluR2 and GluR3

Based on the strong sequence similarity between the proteins encoded by GluR1, GluR2 and GluR3, the following experiments were conducted to determine if the GluR2 and GluR3 proteins might function as homomeric, kainate-sensitive ion channels in Xenopus oocytes (as is the case with GluR1). Thus, oocytes were injected with in vitro synthesized RNA transcripts derived from individual cDNA clones. FIG. 3 presents a comparison of current responses measured in Xenopus oocytes injected with individual GluR1, GluR2 and GluR3 subunit RNAs or rat brain hippocampus poly(A)⁺ RNA. FIG. 3A shows responses of oocytes to 100 mM KA measured 3 days after injection of individual GluR1 (2 ng), GluR2 (10 ng) or GluR3 (2 ng) RNA. The insert shows examples of voltage recording traces obtained from such oocytes except that the GluR2 response was obtained 5 days after injection of 25 ng RNA. The figure further shows that both GluR2 and GluR3 injected oocytes depolarize in response to batch application of 100 μM KA.

The amplitudes of the KA responses were not equivalent for the three glutamate receptor subunits: with equal amounts of injected RNA (2 ng), responses in GluR3 RNA-injected oocytes were invariably larger than GluR1 responses. KA-invoked depolarizations in GluR2-injected oocytes were the weakest and could only be detected in oocytes injected with much larger amounts of RNA (10 to 25 ng).

The data in FIG. 3B represent the responses of oocytes to the indicated agonists measured 3 days after injection with GluR1 (2 ng) or GluR3 (2 ng) RNA or adult rat brain hippocampus poly(A)⁺ RNA (˜50 ng). All values are normalized to the response obtained with 100 mM KA and are presented as the mean±S.E.M. with n≧3 for all measurements. All oocytes were voltage-clamped to -70 mV and recordings were performed as described by Hollmann et al., Nature 342:643 (1989). The data show that, in addition to KA, oocytes injected with GluR1 or GluR3 RNA also respond to QUIS (10 μM), AMPA (50 μM), and glutamate (GLU, 100 μM). No detectable responses were obtained with NMDA (30 μM plus 10 μM glycine) or APB (50 μM). Responses obtained from oocytes injected with GluR2 RNA were too small for reproducible quantitation and were, therefore, excluded from the analysis. For GluR1-injected oocytes, the responses to AMPA and QUIS were typically 35-40% of the maximal KA response, while for GluR3-injected oocytes they were about 10% of the KA response. Relative to KA, the response of GluR1 to domoic acid (DOM, 10 μM) is about 6-fold greater than that seen for GluR3. Taken together these data demonstrate that receptors assembled from GluR1 or GluR3 subunits are pharmacologically distinct. Furthermore, the observation that homomeric GluR1 and GluR3 receptors respond to both QUIS and AMPA, albeit with reduced efficiencies, provides direct evidence that KA, QUIS and AMPA can bind to the same glutamate receptor polypeptide.

FIG. 3B also shows that the pharmacological profile of oocytes injected with individual GluR1 or GluR3 subunit RNA is significantly different than that seen in oocytes injected with rat brain hippocampus poly(A)⁺ RNA. This suggests that the response seen in oocytes injected with hippocampus RNA is mediated by heteromeric glutamate receptors assembled from various combinations of GluR1, GluR2 and GluR3 subunit polypeptides. This suggestion is supported by the fact that all three GluR subunit genes are actively transcribed in the hippocampus.

Example X Pharmacological Comparison of GluR1, GluR2 and GluR3

This example addresses the question of whether glutamate receptors assembled from mixtures of proteins encoded by the GluR₁, GluR2 and GluR3 subunit genes have pharmacological properties significantly different from each other or from those observed for single subunit receptors. FIG. 4 presents a comparison of current responses measured in Xenopus oocytes injected with combinations of GluR1, GluR2 and GluR3 RNAs.

A comparison of the data in FIGS. 3B and 4B suggests that, for the agonists tested, there are few substantial differences in the pharmacology. FIG. 4B summarizes the responses of oocytes to the indicated agonists measured 3 days after injection of 2 ng RNA for each of the indicated GluR subunits or 50 ng rat brain hippocampus poly(A)⁺ RNA. Values have been normalized to the response obtained with 100 mM KA and are presented as the mean±S.E.M. with n≧3 for all measurements. All oocytes were clamped to -70 mV and recordings performed as described by Hollmann et al. Nature 341:643 (1989)!. Responses to QUIS, AMPA and GLU are, relative to GluR1, significantly reduced in the oocytes expressing the subunit combinations. Except for the NMDA response, the overall agonist profiles for oocytes injected with GluR subunit combinations are more similar to oocytes containing hippocampus poly(A)⁺ RNA than to those injected with either GluR1 or GluR3 subunit RNA alone.

Example XI Comparison of KA-Activated Currents Recorded from GluR1, GluR2 and GluR3

FIG. 4A presents the responses of oocytes to 100 mM KA measured 3 days after injection of 2 ng RNA for each of the indicated GluR subunit combinations. The open columns represent the sum of the responses measured in oocytes expressing the individual GluR subunit RNAS, while the stippled columns show the measured amplitudes after expression of combinations of the GluR subunit RNAs in individual oocytes. The figure compares KA-activated currents recorded from oocytes injected with mixtures of GluR1, GluR2 and GluR3 subunit (stippled columns) with the summed currents measured for the individual subunits (blank columns).

The principle finding is a significant potentiation of KA-evoked currents in oocytes coexpressing glutamate receptor subunits. For example, co-expression of GluR1 plus GluR2 yields an approximately 4-fold increase over the summed responses for singly-injected oocytes; or co-expression of GluR2 plus GluR3 subunits yields an approximately 2-fold increase. Injection of all three subunit RNAs results in an average 2.5 fold-increase in KA-evoked currents.

These results indicate that, in oocytes, individual glutamate receptor subunit polypeptides do not behave in a simple independent fashion. Instead, the various subunits apparently interact with each other, by the generation of heteromeric glutamate receptors with properties which are distinct from the receptors comprised of solitary glutamate receptor subunits.

Example XII Current-Voltage Relationships for KA-Evoked Responses

This example examines the current-voltage (I/V) relationships for KA-evoked responses measured in oocytes injected with individual GluR subunits, combinations thereof, or hippocampus poly(A)⁺ RNA.

The I/V data are illustrated in FIG. 5 where the dependence of current response to exposure to 100 mM KA upon the membrane potential is shown. Data obtained from oocytes injected with individual glutamate receptor subunit RNAs are shown in panel A, data obtained from oocytes injected with combinations of subunits are shown in panels B and C, and for purposes of comparison, data obtained from oocytes expressing hippocampus poly(A)⁺ RNA are also shown in panel A, where data obtained from oocytes injected with rat brain hippocampus poly(A)⁺ RNA (50 ng) are indicated by a Solid Square (▪), oocytes injected with GluR1 RNA are indicated by an Open Square (□) or oocytes injected with GluR3 RNA are indicated by an Open Circle (∘); (B) oocytes injected with GluR1 plus GluR2 RNAs are indicated by a Solid Square (▪) or oocytes injected with GluR1 plus GluR3 RNAs are indicated by an Open Square (□); and (C) oocytes injected with GluR2 plus GluR3 RNAs are indicated by a Solid Square (▪) or oocytes injected with all three GluR subunit RNAs are indicated by an Open Square (□). Recordings were made from oocytes 3 days after injection of 2 ng RNA for each GluR subunit. Voltages were stepped by 10 mV between -150 mV and +50 mV; all values are normalized to the response measured at -70 mV.

The KA responses measured in oocytes injected with brain poly(A)⁺ RNA show an approximately linear I/V relationship with a reversal potential of about -10 mV. This result is in marked contrast to the I/V curves obtained for oocytes injected with single GluR1 or GluR3 subunit RNA. The GluR1 and GluR3 I/V curves show strong inward rectification and reversal potentials near -40 mV. From these data it is clear that the KA-sensitive receptors present in oocytes injected with hippocampus RNA are different from those assembled by oocytes injected with GluR1 or GluR3 subunit RNAs.

In FIG. 5B the I/V curve for the GluR1 plus GluR2 combination is noticeably different from that observed for the GluR1 subunit alone. Oocytes injected with this pair of RNAs show a nearly linear I/V plot and have a reversal potential of approximately -10 mV. This plot is strikingly similar to that seen with hippocampus RNA-injected oocytes (panel A). In contrast, the I/V curve for the GluR1 plus GluR3 combination is only marginally different from those measured in oocytes expressing the individual subunits.

FIG. 5C shows some inward rectification in the I/V curve for the GluR2 plus GluR3 subunit combination, as well as a reversal potential somewhat more negative (-20 mV) than those determined for GluR1 plus GluR2 or hippocampus RNA I/V plots (-10 mV). When all three glutamate receptor subunit RNAs are combined in a single oocyte, the resulting I/V curve approximates that seen for the GluR1 plus GluR2 combination in both reversal potential and slope; however, the responses with the three subunits show a pronounced inward rectification not observed with GluR1 plus GluR2.

Example XIII Distribution of GluR1, GluR2 and GluR3 mRNA in the Mammalian Central Nervous System

The distribution of GluR1, GluR2 and GluR3 RNAs in the adult rat brain was examined to test the hypothesis that proteins encoded by the GluR1, GluR2 and GluR3 genes assemble to form heteromeric glutamate receptors in vivo. This hypothesis would be rendered highly unlikely by a showing that the individual subunit genes are transcribed in different neuroanatomical loci. The distribution of the variou subunit RNAs was examined using radiolabeled anti-sense RNA probes and in situ hybridization histochemistry essentially as described by Deneris et al. J. Biol. Chem. 264:6268 (1989)!. The hybridization patterns obtained with the GluR₁, GluR2 and GluR3 probes were nearly identical, with the strongest hybridization seen in the CA1-CA3 regions of the hippocampus and the dentate gyrus. High-resolution analysis of these areas suggests that the hybridization signal originates in the pyramidal cell layer of regions CA1-CA3 and the granule cell layer of the dentate gyrus. Somewhat weaker hybridization of all three probes was seen in the piriform cortex, caudate-putamen, amygdala, and hypothalamus. Low levels of hybridization were detected in the thalamus, with little or no signal observed in fiber tracts. While differential hybridization was seen in the medial habenula and neocortex, the overall patterns of expression for the GluR1₁, GluR2 and GluR3 subunit genes showed substantial concordance.

Example XIV Isolation of cDNAs for GluR4 and GluR5

GluR4:

Using a fragment of the GluR2 cDNA (nucleotides 1793-2240) as a probe in a low stringency hybridization protocol (as per Example II), several GluR4 and GluR5 clones were isolated from a rat forebrain library (as described in Example VIII). Sequence analysis demonstrated that none of the cDNA clones contained an entire open reading frame. Northern blots with mRNA from different adult rat brain tissues indicated that the GluR4 and GluR5 transcripts were most abundant in the cerebellum. Consequently, the partial GluR4 and GluR5 cDNA clones were used as probes under high stringency screening conditions to isolate cDNAs encoding large open reading frames from an adult rat cerebellum cDNA library constructed in the vector λZAP.

Of the cDNA clones thus isolated, two GluR4-related clones (λCER112 and λCER121B) encoded only portions of the GluR4 gene but possessed sufficient overlap to engineer a full-length, expressible construct in the pBS SK (+) vector (Stratagene Cloning Systems, La Jolla, Calif.). The nucleotide sequence of this GluR4 construct, designated pK45, was determined and is presented in Sequence ID No. 7, along with the deduced amino acid sequence therefor.

The GluR4 mRNA was detected on Northern blots of cerebellum RNA as a 4.6 kb species. The smaller size mRNA may represent splice variants.

GluR5:

Among the 29 GluR5-related cDNAs isolated from the cerebellum library, three clones, specified λRB12, λRBl5 and λRB20, were identified which encode an identical large open reading frame. The sequence of cDNA clone λRB20 (GluR5-1) is shown in Sequence ID No. 9. Cleavage of the assumed signal peptide is predicted to occur between amino acid positions 30 and 31 von Heijne, Nucl. Acids Res 14:4683 (1986)!. This cleavage site is after a proline residue, which is atypical. The signal peptide is encoded by a fragment of about 30 amino acids. Potential sites of N-linked glycosylation are found at Asn-68, Asn-74, Asn-276, Asn-379, Asn-428, Asn-439, Asn-620 and Asn-766.

λRB15 and λRB12 are shorter than λRB20 at the 5' end. The λRB20 cDNA consists of a 5' untranslated region of 187 bp, a continuous open reading frame of 2760 bp, and a 3' untranslated region of 303 bp. The 5' untranslated region ends with the sequence AAGATGG, which is characteristic of a translational start site.

Three additional cDNA clones originally isolated from the forebrain library were also examined. The sequences of these cDNAs are identical to λRB20 in the predicted translation initiation site region. Sequence analysis revealed that two variants of the GluR5 cDNA are represented in the forebrain and the cerebellum libraries. This heterogeneity derives from the insertion of 45 nucleotides (found in λRB20 and 17 of the 29 GluR5-related cDNA clones isolated). The insertion of 45 nucleotides, as found in λRB20, but not in 12 of the 29 cDNA clones isolated, occurs between nucleotides 1388 and 1434. This insertion does not interrupt the open reading frame. Furthermore, consensus splice donor and acceptor sites are absent Breathnach and Chambon, Ann. Rev. Biochem. 50:349-383 (1981)!, which suggests that the insertion does not arise from an unspliced intron and is, most likely, the result of an alternative splice event. Nucleotide sequence analysis indicates that the two GluR5 variants are otherwise identical.

No cDNA clone was found for the shorter splice variant encoding the entire open reading frame. Therefore a clone (λRBΔ20) was constructed that is missing the 45 nucleotide insertion found in λRB20 (GluR5-1) but is otherwise identical to that clone. The shorter splice variant clone (λRBΔ20) is referred to as GluR5-2. Both λRB20 and λRBΔ20 were used in Xenopus oocyte expression experiments (see Example XVI) and the variant proteins encoded were named GluR5-1 and GluR5-2, respectively.

Northern blot analysis of cerebellum RNA indicated that the major GluR5 mRNA has a size of 6 kilobases.

Example XV Structural Features of GluR5 cDNA and Protein

Translation of the cDNA nucleotide sequence for GluR5-1 predicts a single long open reading frame of 920 amino acid residues (see Sequence ID No. 9). The GluR5 sequence has overall amino acid sequence identity with each of the KA/AMPA subunits (see FIG. 2, and Table 1). The 15 amino acid insertion in GluR5-1 is unique among the proteins listed, thus the shorter GluR5-2 variant is the counterpart to the KA/AMPA subunits characterized. Table 1 shows that GluR5 is thus far the most dissimilar glutamate receptor subunit identified; and the comparison of GluR5 with the KA/AMPA subunits highlights the most conserved sequence elements (FIG. 2). Within other ligand-gated ion channel families (i.e., the neuronal nicotinic acetylcholine receptors (nAChR), the GABA_(A) receptors and the glycine receptors), the N-terminal extracellular domain is most conserved while the C-terminal sequences diverge between the membrane-spanning regions (MSR) III and IV. In the glutamate receptor subunit gene family, in contrast, the regions N-terminal of the proposed MSR I Hollmann et al., Nature 342:643 (1989)!, have only 17% identity and are less similar than the regions C-terminal of MSR I which have 45% identity. The `Cys-Cys loop`, a signature for ligand-gated neurotransmitter receptor channel complexes Barnard et al., Trends Neurosci. 10:502 (1987)! is not conserved in the glutamate receptor subunit family (FIG. 2). The C-terminal half of glutamate receptor subunits is thought to be involved in channel formation and contain the membrane spanning regions (MSR I-IV; FIG. 2). The presumed MSR III is the most conserved continuous sequence, with only one conservative amino acid exchange (Val to Ile) in the GluR5 protein (FIG. 2). As mentioned above, in other ligand-gated channel families the segment between MSR III and IV is divergent in length and sequence. In the glutamate receptor subunit family the similarity in this postulated segment is high (48%) and only GluR5 exhibits a sequence length variation. The KA/AMPA receptors and the GlUR5 protein are generally divergent C-terminal of the proposed MSR IV.

The hydrophobicity plot for GluR5 is similar to those of the KA/AMPA receptors, suggesting a conserved secondary structure in the proposed ion channel forming portion of the protein. However, the N-terminal half of the GluR5 hydrophobicity plot is unusual. In this region, GluR5, as compared to the KA/AMPA subunits, is more hydrophobic and contains several segments that could span the membrane. Based on algorithms that search for membrane-associated helices, four Rao and Argos, Biochim. Biophys. Acta 869:197-214 (1986)! or seven Eisenberg et al., J. Mol. Biol. 179:125-142 (1984)! putative transmembrane regions can be assigned to GluR5.

A comparison of the C-terminal regions of all five glutamate receptor subunits with the frog Gregor et al., Nature 342:689 (1989)! and chicken Wada et al., Nature 342:684 (1989)! KA binding proteins demonstrates a similar extent of sequence conservation (35-40% amino acid identity). A FASTA search Pearson and Lipman, Proc. Natl. Acad. Sci. USA 85:2444 (1988)! of the GenBank, EMBL and SWISS-PROT databases with the GluR5 sequence uncovered no significant similarities to other proteins.

Example XVI Electrophysiological Properties of GluR5 mRNA Injected Oocytes Exposed to L-Glutamate

In vitro synthesized GluR5-1 and GluR5-2 cRNAs were individually expressed in Xenopus oocytes. With either cRNA, the glutamate receptor agonists KA (100 MM), AMPA (50 μM), quisqualate (10 μM), APB (100 μM) and NMDA (100 μM, applied with 10 μM glycine) did not elicit membrane depolarizations in cRNA injected oocytes. However, weak membrane depolarizations induced by L-glutamate (100 μM) were recorded in oocytes injected with GluR5-l cRNA (maximal depolarization 3.5 mV) and GluR5-2 cRNA (maximal depolarization 4.5 mV). Significantly stronger membrane depolarizations were not found in response to L-glutamate in oocytes co-injected with GluR5-1 and GluR5-2 RNA as compared to oocytes injected with GluR5-2 cRNA alone. For any particular oocyte injected with GluR5-1 or GluR5-2 cRNA, the depolarizations were reproducible, showed fast onset, and were slowly (within 5 minutes) reversed when agonist superfusion was switched to buffer superfusion. Neither un-injected oocytes nor water-injected oocytes showed a response to the glutamate receptor agonists tested. Responses to L-glutamate were recorded in 7 (out of 7) oocytes for GluR5-1 (membrane depolarization 2.29±0.26 mV S.E.M.) and 29 (out of 33) oocytes for GluR5-2 (2.27±0.19 mV S.E.M).

Example XVII Distribution of GluR4 and GluR5 mRNA In the Developing Central and Peripheral Nervous Systems

For the developmental study of GluR4 and GluR5 gene expression, sections of mice from embryonic day 10 (E10) through post natal day 21 (P21) were analyzed using in situ hybridization and histochemistry.

In the entire central nervous system (CNS), a diffuse expression of the GluR4 and GluR5 genes was detected at E10. These first hybridization signals originate from postmitotic neurons. This is best demonstrated in the myelencephalon at E12. The ependymal layer is facing the neural canal and contains dividing neuroblasts. No hybridization was detectable in these cells. The postmitotic cells are located in the exterior part of the neural tube and express both genes.

Later in development, transcripts for GluR5 and, to a lesser extent, GluR4 were particularly pronounced in areas where neurons differentiate and assemble into nuclei. These temporal changes in the hybridization pattern were best observed for GluR5 (in the primary sensory nuclei of the medulla oblongata and the nuclei of the pons which hybridized more intensely than surrounding structures at E14). GluR5 gene expression was particularly intense in several discrete brain nuclei, whereas GluR4 gene expression was detectable over the entire rostral and caudal parts of the brain.

During postnatal development, the spatial distribution of GluR4 gene transcripts did not change but usually smaller amounts of mRNA were detectable than at late embryonic stages. In contrast, GluR5 gene expression appeared to become more restricted spatially during development, and transcript levels were down-regulated. Extreme changes in the temporal GluR5 hybridization pattern were apparent in the cerebellar cortex. Until P12, high GluR5 transcript levels were detected in the granular and Purkinje cell layer. Later, the intensity of hybridization signals in the granular cell layer was reduced relative to the Purkinje cell layer and starting at P14, only a faint hybridization signal was detected in the granular cell layer.

In general, those regions of the brain that exhibited a dense labeling during embryonic development also had detectable transcript levels in adults. In P21 animals, the highest GluR4 transcript levels were observed in the cell layers of the olfactory bulb, the hippocampus, the cerebellum and the retina. In the retina, strong hybridization was found in the ganglion cell layer and in the amacrine cells of the inner nuclear layer. No expression was detected in Muller cells. For GluR5, the strongest hybridization signals at P21 were found in the olfactory bulb, the amygdala, the colliculi and some hypothalamic nuclei.

In the developing peripheral nervous system (PNS), the hybridization assays showed that the GluR4 and GluR5 genes are expressed to varying degrees in the cranial ganglia (e.g., trigeminal ganglion, acoustic ganglia), dorsal root ganglia and the mural ganglia of the intestinal organs. Comparable to the CNS, transcripts in the PNS are detected by E10 for GluR4 and by E11 for GluR5. During development, hybridization signals for GluR4 continuously increase until early postnatal stages and then persist with similar intensity in adults. Hybridization signals for GluR5 increase up to E16 and remain with comparable intensity in later developmental stages. In postnatal animals, the dorsal root ganglia (GluR5) and the mural Ganglia of the intestinal organs (GluR4 and GluR5) exhibit higher levels of hybridization than the CNS. High resolution autoradiography in the dorsal root ganglia demonstrates hybridization of the GluR5 probe over neuronal cells whereas satellite cells are unlabeled.

Example XVIII Distribution of GluR4 and GluR5 mRNA in the Adult Mammalian (Rat) Brain

The distribution of the GluR4 and GluR5 mRNA transcripts in the adult CNS was studied by in situ hybridization. In the forebrain region, high levels of GluR4 transcripts were detected in the CA1 and the dentate gyrus of the hippocampus, in the medial habenula and particularly in the reticular thalamic nucleus. The hippocampus showed only weak expression of the GluR5 gene and no transcripts were detected in the medial habenula. The GluR5 hybridization signal was intense in the cingulate and piriform cortex, several hypothalamic nuclei, the amygdala and the lateral septum. In the cerebellum, the hybridization patterns for GluR4 and GluR5 probes were overlapping but distinct. Both probes were detected at high levels in the Purkinje cell layer. In the granular cell layer the GluR4 probe produced strong labeling, while GluR5 probe labeling was weak.

Example XIX Isolation of GluR6 and GluR7

cDNA clones encoding the GluR6 and GluR7 genes were isolated from an adult rat forebrain library using a low-stringency hybridization screening protocol (see Example II) and a radiolabeled fragment of about 1.2 kbp (nucleotides 705-2048) of the GluR5 cDNA as a probe. The selected clones were identified by restriction digest map and sequencing.

An adult rat cerebellum cDNA library constructed in λZAP was screened under low-stringency hybridization conditions with the above-described GluR5 cDNA fragment Bettler et al., Neuron 5: 583-595 (1990)!. A 3kb fragment from a cDNA clone encoding part of the GluR6 open reading frame was used to rescreen the library under high-stringency hybridization conditions. Two clones, RC11 and RC27, possessed sufficient overlap to engineer a cDNA clone encoding the entire open reading frame of the GluR6 protein.

A 4559 base pair cDNA encoding a protein of 884 amino acid residues was engineered from RC11 and RC27. The protein encoded by this cDNA is referred to as GluR6. Sequence ID No. 11 shows the nucleotide and deduced amino acid sequence of the GluR6 clone. The similarity between the hydropathy profile of the GluR6 subunit and those of the GluR1-GluR5 subunits suggests a similar membrane spanning topology.

Another adult rat cerebellum cDNA library was constructed in λZAP and screened under low-stringency hybridization conditions with the above-described GluR5 cDNA fragment. A 2kb fragment from a cDNA clone encoding part of the GluR7 open reading frame was used to rescreen the library under high-stringency hybridization conditions. Two clones, RP52 and RPC44, possessed sufficient overlap to engineer a cDNA clone encoding the entire open reading frame of the mature GluR7 protein.

A 3344 base pair cDNA encoding a protein of 921 amino acid residues was engineered from RP52 and RPC44. The protein encoded by this cDNA is referred to as GluR7. Sequence ID No. 13 shows the nucleotide and deduced amino acid sequence for the GluR7 clone.

The physiological and pharmacological properties of the homomeric GluR6 ion channel were studied in Xenopus oocytes injected with in vitro transcribed RNA. In oocytes held at -100 mV, application of kainate and glutamate evoked inward currents that desensitized in continued presence of agonist. Full recovery from desensitization caused by application of 100 μM kainate for 30 seconds required approximately 15 minutes. Quisqualate activated only small inward currents; however, quisqualate application attenuated a subsequent kainate evoked current. AMPA (100 μM) did not evoke any detectable current, nor did it antagonize a kainate-evoked current when AMPA and kainate were applied together. The AMPA solution used in the experiment did evoke responses in oocytes injected with either hippocampal mRNA or GluR1 RNA (which are both known to respond to AMPA).

Exposure of the injected oocyte to 10 μM concanavalin A (Con A) for 5 minutes efficiently decreases desensitization see Meyer & Vyklicky, Proc. Natl. Acad. Sci. USA 86: 1411-1415 (1989)! and allows agonist-activated currents mediated by the GluR6 receptor to be more easily studied. Con A treatment increased current elicited by kainate and glutamate by 75 to 150fold compared to the peak current for equimolar concentrations before the treatment. After Con A treatment, the maximal current induced by glutamate (relative to kainate) was 0.56±0.03 and for quisqualate 0.38±0.03. Con A treated oocytes injected with GluR6 RNA responded to kainate, but did not respond to application of 100 μM aspartate, 100 μM NMDA in the presence of 3 μM glycine, or 10-1000 μM AMPA. Furthermore, coapplication of AMPA (100 μM) had no effect on the kainate-evoked (1 μM) responses on Con A treated oocytes. It thus appears that AMPA acts as an agonist on only a subset of the kainate/quisqualate sensitive ionotropic receptors.

The dose response curves for activation of the GluR6 receptor were obtained after Con A treatment. Data are summarized in Table 3, and in FIG. 7a, which presents dose-response curves obtained on GluR6 injected oocytes after Con A treatment for kainate (◯), glutamate (□), quisqualate (Δ) and kainate in the presence of 10 μM 6-nitro-7-cyano-quinoxaline-2,3-dione (CNQX) (). All points represent an average of 3-6 independent measurements. Error bars indicate S.E.M.

                  TABLE 3                                                          ______________________________________                                         EC.sub.50 and the Maximal Agonist-evoked Current Relative                      to the Maximal Kainate-evoked Current for Homomeric                            GluR6 Receptor After Con A Treatment                                                                 Relative maximal current                                 Agonist     EC.sub.50 (μM)                                                                        (±S.E.M.)                                             ______________________________________                                         Kainate     1.0 (0.8-1.3)                                                                            1.00                                                     Quisqualate  11 (10-13)                                                                              0.38 ± .03                                            Glutamate    31 (29-34)                                                                              0.56 ± .03                                            ______________________________________                                          The mean of EC.sub.50 are based on measurements of 3-6 oocytes. The            numbers in parentheses indicate 95% confidence intervals. Relative maximu      current maximum agonistevoked current/maximum kainateevoked current.     

The EC₅₀ for kainate (1 μM) is about 35-fold lower than the EC₅₀ observed for the homomeric GluR1 (EC₅₀ =35 μM) receptor see Hollmann et al., Nature 242: 643-648 (1989); Dawson et al., Mol. Pharmacol. 38: 779-784 (1990)!. The EC₅₀ for the GluR6 receptor is 75-fold higher for quisqualate and 10-fold higher for glutamate when compared to the same agonist on the GluR1 receptor. Thus the order of agonist potency for the homomeric GluR6 receptor is:

    kainate>quisqualate>L-glutamate.

The order of agonist potency set forth above is similar to the order of binding affinities measured for quisqualate and glutamate as competitive displacers of kainate on kainate binding sites in isolated brain membranes see Foster and Fagg, Brain Res. Rev. 7: 103-164 (1984)!. This property is clearly distinct from the GluR1 and GluR3 receptors where the relative apparent affinities are:

    quisqualate>AMPA>glutamate>kainate.

See Nakanishi et al., Neuron 5: 569-581 (1990); Boulter et al., Science 249: 1033-1037 (1990); and Foster and Fagg, supra!. Therefore, based on agonist potencies (EC₅₀), GluR6 can be considered a kainate receptor within the glutamate receptor family.

CNQX acts as a competitive antagonist of non-NMDA receptors in rat brain neurons see Verdoorn et al., Mol. Pharmacol. 35: 360-368 (1989)!. CNQX blocked both quisqualate and kainate-evoked responses in oocytes injected with GluR6 RNA. The inhibitory effect of 10 μM CNQX was eliminated at high kainate concentrations, consistent with its competitive mode of action. 10 μM CNQX resulted in a 3.5-fold parallel shift of the kainate dose-response curve compared to the curve obtained in absence of CNQX (see FIG. 7a). Considering the competitive action of CNQX at 10 μM, the K_(i) for CNQX was calculated to be 4 μM. Thus, CNQX is a less potent blocker of kainate responses at GluR6 receptors than at GluR1 receptors (K_(i) =0.519 μM) see Dawson et al, supra! and kainate receptors derived from forebrain mRNA (K_(i) =0.295 μM) see Verdoorn et al., supra! expressed in oocytes.

The current-voltage relationship (I/V) for kainate and glutamate-evoked responses in the presence of Con A and for kainate in the absence of Con A was examined. No qualitative differences were found between Con A-treated and untreated oocytes (see FIG. 7b). The I/V relationships were assessed from 2 s voltage ramps from -100 mV to 50 mV in the presence and absence of agonist. Data were collected and analyzed using the pclamp program set. The I/V relationship exhibited a reversal potential of -10±3 mV and an outward rectification. To analyze whether the outward rectification was an intrinsic property of the channel (or perhaps an activation of endogenous chloride channels activated by a Ca⁺⁺ flux see Miledi & Parker, J. Physiol. 357: 173-183 (1984)! through the GluR6 ion channel), the kainate-evoked I/V relationship was recorded in a buffer where 95% of the Cl⁻ ions were substituted by an equimolar amount of methanesulfonate (which is known to shift the chloride reversal potential in a positive direction see Verdoorn & Dingledine, Mol. Pharmacol. 34: 298-307 (1988)!). No significant change in the reversal potential was observed. Thus, if there is a Ca⁺⁺ flux in Ringer solution, it is not sufficient to activate a Cl⁻ current. The substitution of Cl⁻ with methanesulfonate reduced the current 8-fold; this may have been caused by either inhibition of agonist binding or a direct methanesulfonate block of the channel. The latter effect might be potentiated at positive holding potentials.

The expression pattern of the GluR6 gene was studied by in situ hybridization using brain sections from adult mice. The highest levels of GluR6 transcripts were observed in the olfactory lobe, piriform cortex, dentate gyrus, hippocampus, and in the granular cell layer of the cerebellum. In the hippocampus a gradient in hybridization intensities was observed from rostral to caudal areas, with increased intensity in the CA3 region as compared to the CA1 region. The high level of transcripts in the pyramidal cell layer of CA3 and the granule cell layer of the dentate gyrus correlates with the previously observed high level of ³ H!kainate binding in the stratum lucidum and the commissural/associational terminal field of the dentate gyrus, respectively see Foster and Fagg, supra; and Monaghan & Cotman, Brain Res. 252: 91-100 (1982)!. Less intense hybridization signals were observed in the caudate putamen, the zona incerta of the thalamus, the inner and outer layers of cortex, several brain stem nuclei as well as the ganglion cell layer of the retina. In general, areas expressing high level of transcripts correlate well with areas expressing high affinity kainate binding sites.

The properties observed herein for the homomeric GluR6 receptors have not been described in studies performed on neurons. The pattern of the gene expression and the pharmacology of the GluR6 subunit suggest that this subunit might correspond or contribute to the receptor with high affinity for kainate found in the brain.

Example XX GluR-Related Assays

The GluR cDNAs, mRNAs, proteins and functional fragments thereof, are useful in various assays designed to identify and characterize L-glutamate receptors, agonists and antagonists. For example, the cDNAs are useful as probes to identify additional members of the glutamate receptor gene family. mRNAs transcribed from the DNAs of the invention are especially useful in assays designed to identify and characterize both functional receptors and ligands. This use is especially important for the identification and design of compounds that can affect L-glutamate receptor function.

In an assay for identifying and characterizing functional receptors, mRNA is transcribed from DNAs of the invention (either full length or fragments thereof produced by deletions, substitutions, synthesis, etc.) and then translated to produce GluR proteins. In a presently preferred means for carrying out this transcription and translation, the mRNAs are translated in oocytes, preferably Xenopus oocytes. Alternatively, suitable cultured mammalian cells can be used as hosts for the production of glutamate receptor proteins. Such mammalian cells can be transfected in vitro with DNAs of the invention to yield either stable or transiently transfected cell lines. The expressed glutamate receptor proteins are then exposed to ligands known to functionally bind to and activate glutamate receptors. The physiological characteristics of the glutamate receptor proteins are measured by suitable means (e.g., by electrophysiology), and those that form functional ion channels are concluded to be functional glutamate receptor.

In a related assay designed to identify functional ligands for glutamate receptors, proteins known to functionally bind to glutamate receptor agonist or antagonist compound(s) are contacted with at least one "unknown" or test compound whose ability to effect the ion channel activity of glutamate receptors is sought to be determined (in the optional presence of a known glutamate agonist, where antagonist activity is being tested). The electrophysiological properties of the glutamate receptors are measured following exposure to the test compound(s), and those that affect the ion channel response are concluded to be functional ligands for glutamate receptors.

Without departing from the spirit and scope of this invention, one of ordinary skill can make various changes and modifications to the invention to adapt it to various usages and conditions. As such, these changes and modifications are properly, equitably, and intended to be, within the full range of equivalence of the following claims.

SUMMARY OF SEQUENCES

Sequence ID No. 1 shows the nucleotide and deduced amino acid sequence of the clone GluR1.

Sequence ID No. 2 is the deduced amino acid sequence of the clone GluR1.

Sequence ID No. 3 shows the nucleotide and deduced amino acid sequence of the clone GluR2.

Sequence ID No. 4 is the deduced amino acid sequence of the clone GluR2.

Sequence ID No. 5 shows the nucleotide and deduced amino acid sequence of the clone GluR3.

Sequence ID No. 6 is the deduced amino acid sequence of the clone GluR3.

Sequence ID No. 7 shows the nucleotide and deduced amino acid sequence of the clone GluR4.

Sequence ID No. 8 is the deduced amino acid sequence of the clone GluR4.

Sequence ID No. 9 shows the nucleotide and deduced amino acid sequence of the cDNA clone encoding glutamate receptor subunit GluR5-1.

Sequence ID No. 10 is the deduced amino acid sequence of the clone GluR5.

Sequence ID No. 11 shows the nucleotide and deduced amino acid sequence of the clone GluR6.

Sequence ID No. 12 is the deduced amino acid sequence of the clone GluR6.

Sequence ID No. 13 shows the nucleotide and deduced amino acid sequence of fragments clone GluR7.

Sequence ID No. 14 is the deduced amino acid sequence of the clone GluR7.

    __________________________________________________________________________     #             SEQUENCE LISTING                                                 - (1) GENERAL INFORMATION:                                                     -    (iii) NUMBER OF SEQUENCES: 14                                             - (2) INFORMATION FOR SEQ ID NO:1:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 2992 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR1                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 198...2918                                                       (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:                                  #CGGAAGGAAG    60CTCGGCT CCCCTTCCAA GAGAAACAAG AGAAACCTCA                      #GAGCATCAAG   120AAGCAAG CAAGGAACTG CAGGAAGAAA AGAGCCGGCA                      #TTCTTTTTCG   180AGGGGAG GGAAGACCAA ATCTATGGTT GGACCAGGGC                      -  CCAATGTAAA AAGGAAT ATG CCG TAC ATC TTT GCC T - #TT TTC TGC ACC GGT           230                                                                           #Thr Glyro Tyr Ile Phe Ala Phe Phe Cys                                         #10                                                                            #CCC AAC AAT ATC CAG ATA     278CC AAT TTC                                     #Pro Asn Asn Ile Gln Ile Gly Ala Asn Phe                                       #             25                                                               #GAA CAT GCG GCT TTT AGG     326AA TCA CAG                                     #Glu His Ala Ala Phe Arg Gln Gln Ser Gln                                       #         40                                                                   #AAG CTG CTT CCC CAG ATC     374AG CCC CCC                                     #Lys Leu Leu Pro Gln Ile Thr Glu Pro Pro                                       #     55                                                                       #ATG ACT TAC CGT TTC TGT     422CG TTT GAG                                     #Met Thr Tyr Arg Phe Cys Asp Thr Phe Glu                                       # 75                                                                           #TTT GGA TTT TAT GAA CGA     470AT GCC ATC                                     #Phe Gly Phe Tyr Glu Arg Val Tyr Ala Ile                                       #                 90                                                           #GGG GCC CTC CAT GTG TGC     518CC TTC TGT                                     #Gly Ala Leu His Val Cys Thr Ser Phe Cys                                       #             105                                                              #TCC AAT CAA TTT GTC CTT     566TT GAC ACA                                     #Ser Asn Gln Phe Val Leu Pro Val Asp Thr                                       #        120                                                                   #ATT AGC ATT ATC GAC CAT     614AA GCT CTC                                     #Ile Ser Ile Ile Asp His Gln Glu Ala Leu                                       #    135                                                                       #GAT GCT GAC CGG GGC CTG     662AC ATT TAT                                     #Asp Ala Asp Arg Gly Leu Val Tyr Ile Tyr                                       #155                                                                           #GCA GAG AAG AAC TGG CAG     710AT ACA GCC                                     #Ala Glu Lys Asn Trp Gln Leu Asp Thr Ala                                       #                170                                                           #GAG GAA GGA TAC CGG ATG     758CA ACC ACC                                     #Glu Glu Gly Tyr Arg Met Leu Thr Thr Thr                                       #            185                                                               #AGG CTG GTG GTG GTT GAC     806AA AAG GAG                                     #Arg Leu Val Val Val Asp Lys Lys Lys Glu                                       #        200                                                                   #GGC CAG ATC GTG AAG CTA     854CC ATC CTG                                     #Gly Gln Ile Val Lys Leu Asn Ala Ile Leu                                       #    215                                                                       #CTC GCC AAT CTG GGC TTC     902AC TAC ATC                                     #Leu Ala Asn Leu Gly Phe Tyr His Tyr Ile                                       #235                                                                           #AGC GGA CGC AAT GTG ACA     950TC AAG GAG                                     #Ser Gly Arg Asn Val Thr Lys Phe Lys Glu                                       #                250                                                           #ATC CCA GCC AGA ATC ATG     998CA GAC ACG                                     #Ile Pro Ala Arg Ile Met Tyr Thr Asp Thr                                       #            265                                                               #CAT ACC AGG GTG GAC TGG    1046CC CGA GAC                                     #His Thr Arg Val Asp Trp Asp Ser Arg Asp                                       #        280                                                                   #TAT GAT GGT GTC AAG GTG    1094CT CTC ACC                                     #Tyr Asp Gly Val Lys Val Ser Ala Leu Thr                                       #    295                                                                       #CAG AGG ATT GAC ATA TCC    1142TG CGG AGG                                     #Gln Arg Ile Asp Ile Ser Ser Leu Arg Arg                                       #315                                                                           #AAC CCA GCT GTG CCC TGG    1190GT CTG GCT                                     #Asn Pro Ala Val Pro Trp Asp Cys Leu Ala                                       #                330                                                           #CAG CAG GTG CGC TTC GAA    1238GA GCC CTG                                     #Gln Gln Val Arg Phe Glu Gln Arg Ala Leu                                       #            345                                                               #AAA GGG CGC CGG ACC AAT    1286TC AAC GAG                                     #Lys Gly Arg Arg Thr Asn Gln Phe Asn Glu                                       #        360                                                                   #GAT GGA ATC CGA AAG ATT    1334TG AAA CAT                                     #Asp Gly Ile Arg Lys Ile Glu Met Lys His                                       #    375                                                                       #CCC GCA GCC ACC GAC GCT    1382AA TTT GTC                                     #Pro Ala Ala Thr Asp Ala Asp Lys Phe Val                                       #395                                                                           #AAT AGG ACC TAC ATC GTC    1430GC GTC CAG                                     #Asn Arg Thr Tyr Ile Val Ser Ser Val Gln                                       #                410                                                           #CTT AAA AAG AAT GCC AAC    1478AC GTG ATG                                     #Leu Lys Lys Asn Ala Asn Pro Tyr Val Met                                       #            425                                                               #TAC TGT GTG GAG CTG GCT    1526AT GAG GGC                                     #Tyr Cys Val Glu Leu Ala Arg Tyr Glu Gly                                       #        440                                                                   #TAC CGA CTT GAG ATT GTC    1574GC TAC TCC                                     #Tyr Arg Leu Glu Ile Val Val Gly Tyr Ser                                       #    455                                                                       #GAC ACA AAG GCT TGG AAT    1622GG GAT CCC                                     #Asp Thr Lys Ala Trp Asn Ala Arg Asp Pro                                       #475                                                                           #GCA GAC GTG GCT GTG GCT    1670AT GGA AGA                                     #Ala Asp Val Ala Val Ala Val Tyr Gly Arg                                       #                490                                                           #GTC ATC GAC TTC TCC AAG    1718GG GAG GAA                                     #Val Ile Asp Phe Ser Lys Val Arg Glu Glu                                       #            505                                                               #ATT AAG AAG CCA CAG AAG    1766CC ATT ATG                                     #Ile Lys Lys Pro Gln Lys Ile Ser Ile Met                                       #        520                                                                   #CCT TTG GCC TAT GAG ATC    1814TT CTT GAC                                     #Pro Leu Ala Tyr Glu Ile Ser Phe Leu Asp                                       #    535                                                                       #GTG AGC GTC GTC CTC TTC    1862AC ATT GGA                                     #Val Ser Val Val Leu Phe Ala Tyr Ile Gly                                       #555                                                                           #CAC AGC GAA GAG TTT GAA    1910AC GAA TGG                                     #His Ser Glu Glu Phe Glu Pro Tyr Glu Trp                                       #                570                                                           #TCA AAT GAG TTT GGC ATA    1958GT GAC CAG                                     #Ser Asn Glu Phe Gly Ile Thr Ser Asp Gln                                       #            585                                                               #TTC ATG CAG CAA GGA TGT    2006TG GGG GCC                                     #Phe Met Gln Gln Gly Cys Ser Leu Gly Ala                                       #        600                                                                   #ATC GTC GGC GGC GTC TGG    2054CC GGA CGC                                     #Ile Val Gly Gly Val Trp Leu Ser Gly Arg                                       #    615                                                                       #TAC ACA GCC AAC CTG GCT    2102TC TCC TCG                                     #Tyr Thr Ala Asn Leu Ala Ile Ile Ser Ser                                       #635                                                                           #CCC ATT GAG AGT GCA GAG    2150TG GTG TCT                                     #Pro Ile Glu Ser Ala Glu Arg Met Val Ser                                       #                650                                                           #GGG ACA TTG GAA GCA GGC    2198TT GCT TAT                                     #Gly Thr Leu Glu Ala Gly Glu Ile Ala Tyr                                       #            665                                                               #ATC GCT GTG TTT GAG AAG    2246GA TCT AAA                                     #Ile Ala Val Phe Glu Lys Arg Arg Ser Lys                                       #        680                                                                   #TCC GTG TTT GTT CGG ACC    2294CA GAA CCA                                     #Ser Val Phe Val Arg Thr Ser Ala Glu Pro                                       #    695                                                                       #TCT AAA GGC AAA TAC GCC    2342TG AGA AAA                                     #Ser Lys Gly Lys Tyr Ala Arg Val Arg Lys                                       #715                                                                           #ATT GAG CAA CGA AAG CCC    2390AT GAG TAT                                     #Ile Glu Gln Arg Lys Pro Met Asn Glu Tyr                                       #                730                                                           #GAT TCC AAA GGC TAT GGC    2438GT AAC TTG                                     #Asp Ser Lys Gly Tyr Gly Gly Gly Asn Leu                                       #            745                                                               #AAT CCA GTA AAC CTG GCA    2486CC CTG AGA                                     #Asn Pro Val Asn Leu Ala Ser Ala Leu Arg                                       #        760                                                                   #GAC AAA TTG AAA AAC AAA    2534GG CTT TTG                                     #Asp Lys Leu Lys Asn Lys Gln Gly Leu Leu                                       #    775                                                                       #GGG GGA GGT GAC TCC AAG    2582GC GGC ACG                                     #Gly Gly Gly Asp Ser Lys Glu Cys Gly Thr                                       #795                                                                           #GTG GCA GGC GTG TTC TAC    2630TC AGC AAT                                     #Val Ala Gly Val Phe Tyr Ser Leu Ser Asn                                       #                810                                                           #CTG GTT GCC TTA ATC GAG    2678TG GCC ATG                                     #Leu Val Ala Leu Ile Glu Gly Leu Ala Met                                       #            825                                                               #CGG ATG AAG GGT TTC TGT    2726AG TCG AAG                                     #Arg Met Lys Gly Phe Cys Ser Glu Ser Lys                                       #        840                                                                   #ATA CGG ACA TCG ACC CTC    2774AT GAA GCC                                     #Ile Arg Thr Ser Thr Leu Ile Asn Glu Ala                                       #    855                                                                       #GGA GGC GGC AGT GGA GAG    2822CC AGC GGA                                     #Gly Gly Gly Ser Gly Glu Gly Ala Ser Gly                                       #875                                                                           #AAG TCC ATG CAA TCC ATT    2870AC TTC CCC                                     #Lys Ser Met Gln Ser Ile Gln Asp Phe Pro                                       #                890                                                           #TTG GGA GCC ACA GGA TTG T  2919GG ATG CCC                                     #Leu Gly Ala Thr Gly Leu Ser Gly Met Pro                                       #            905                                                               #CCCATCCCAA  2979AGGAAAC CCTTGGGGAG CAGGCTCAGG CTTCCACAGC                      #    2992                                                                      - (2) INFORMATION FOR SEQ ID NO:2:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 907 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:                                  #Gly Phe Leu Gly Ala Valla Phe Phe Cys Thr                                     #                 15                                                           #Ile Gly Gly Leu Phe Proro Asn Asn Ile Gln                                     #             30                                                               #Arg Phe Ala Leu Ser Glnlu His Ala Ala Phe                                     #         45                                                                   #Ile Asp Ile Val Asn Ileys Leu Leu Pro Gln                                     #     60                                                                       #Cys Ser Gln Phe Ser Lyset Thr Tyr Arg Phe                                     # 80                                                                           #Arg Arg Thr Val Asn Methe Gly Phe Tyr Glu                                     #                 95                                                           #Cys Phe Ile Thr Pro Serly Ala Leu His Val                                     #            110                                                               #Leu Gln Leu Arg Pro Gluer Asn Gln Phe Val                                     #        125                                                                   #His Tyr Lys Trp Gln Thrle Ser Ile Ile Asp                                     #    140                                                                       #Leu Ser Val Leu Gln Argsp Ala Asp Arg Gly                                     #160                                                                           #Gln Val Thr Ala Val Asnla Glu Lys Asn Trp                                     #                175                                                           #Met Leu Phe Gln Asp Leulu Glu Gly Tyr Arg                                     #            190                                                               #Asp Cys Glu Ser Glu Argrg Leu Val Val Val                                     #        205                                                                   #Leu Glu Lys Asn Gly Ilely Gln Ile Val Lys                                     #    220                                                                       #Phe Met Asp Ile Asp Leueu Ala Asn Leu Gly                                     #240                                                                           #Thr Gly Phe Gln Leu Valer Gly Arg Asn Val                                     #                255                                                           #Met Gln Gln Trp Arg Thrle Pro Ala Arg Ile                                     #            270                                                               #Trp Lys Arg Pro Lys Tyris Thr Arg Val Asp                                     #        285                                                                   #Val Met Ala Glu Ala Pheyr Asp Gly Val Lys                                     #    300                                                                       #Ser Arg Arg Gly Asn Alaln Arg Ile Asp Ile                                     #320                                                                           #Trp Gly Gln Gly Ile Aspsn Pro Ala Val Pro                                     #                335                                                           #Glu Gly Leu Thr Gly Asnln Gln Val Arg Phe                                     #            350                                                               #Asn Tyr Thr Leu His Valys Gly Arg Arg Thr                                     #        365                                                                   #Ile Gly Tyr Trp Asn Glusp Gly Ile Arg Lys                                     #    380                                                                       #Ala Gln Ala Gly Gly Aspro Ala Ala Thr Asp                                     #400                                                                           #Val Thr Thr Ile Leu Glusn Arg Thr Tyr Ile                                     #                415                                                           #Asn Gln Phe Glu Gly Asneu Lys Lys Asn Ala                                     #            430                                                               #Ala Ala Glu Ile Ala Lysyr Cys Val Glu Leu                                     #        445                                                                   #Val Ser Asp Gly Lys Tyryr Arg Leu Glu Ile                                     #    460                                                                       #Asn Gly Met Val Gly Glusp Thr Lys Ala Trp                                     #480                                                                           #Ala Pro Leu Thr Ile Thrla Asp Val Ala Val                                     #                495                                                           #Lys Pro Phe Met Ser Leual Ile Asp Phe Ser                                     #            510                                                               #Lys Ser Lys Pro Gly Valle Lys Lys Pro Gln                                     #        525                                                                   #Ile Trp Met Cys Ile Valro Leu Ala Tyr Glu                                     #    540                                                                       #Phe Leu Val Ser Arg Pheal Ser Val Val Leu                                     #560                                                                           #Glu Glu Gly Arg Asp Glnis Ser Glu Glu Phe                                     #                575                                                           #Ile Phe Asn Ser Leu Trper Asn Glu Phe Gly                                     #            590                                                               #Cys Asp Ile Ser Pro Arghe Met Gln Gln Gly                                     #        605                                                                   #Trp Trp Phe Phe Thr Leule Val Gly Gly Val                                     #    620                                                                       #Ala Ala Phe Leu Thr Valyr Thr Ala Asn Leu                                     #640                                                                           #Glu Asp Leu Ala Lys Glnro Ile Glu Ser Ala                                     #                655                                                           #Gly Ser Thr Lys Glu Phely Thr Leu Glu Ala                                     #            670                                                               #Lys Met Trp Thr Tyr Metle Ala Val Phe Glu                                     #        685                                                                   #Thr Thr Glu Glu Gly Meter Val Phe Val Arg                                     #    700                                                                       #Ala Tyr Leu Leu Glu Serer Lys Gly Lys Tyr                                     #720                                                                           #Pro Cys Asp Thr Met Lysle Glu Gln Arg Lys                                     #                735                                                           #Gly Ile Ala Thr Pro Lyssp Ser Lys Gly Tyr                                     #            750                                                               #Ala Val Leu Lys Leu Asnsn Pro Val Asn Leu                                     #        765                                                                   #Lys Trp Trp Tyr Asp Lyssp Lys Leu Lys Asn                                     #    780                                                                       #Lys Asp Lys Thr Ser Alaly Gly Gly Asp Ser                                     #800                                                                           #Tyr Ile Leu Ile Gly Glyal Ala Gly Val Phe                                     #                815                                                           #Glu Phe Cys Tyr Lys Sereu Val Ala Leu Ile                                     #            830                                                               #Cys Leu Ile Pro Gln Glnrg Met Lys Gly Phe                                     #        845                                                                   #Leu Pro Arg Asn Ser Glyle Arg Thr Ser Thr                                     #    860                                                                       #Glu Asn Gly Arg Val Vally Gly Gly Ser Gly                                     #880                                                                           #Ile Pro Cys Met Ser Hisys Ser Met Gln Ser                                     #                895                                                           #Leuer Ser Gly Met Pro Leu Gly Ala Thr Gly                                     #            905                                                               - (2) INFORMATION FOR SEQ ID NO:3:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 3505 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR2                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 316...2964                                                       (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:                                  #ACTACAGCGG    60GGTGCAT GGGAGGGTGC TGATATTCCC AGACACCAGG                      #GGACAGGACG   120AACTGCA TTCAGCCAGT CCTCGGGACT TCGGGAGCAG                      #CTTCACTTCG   180GCCACCA GCTACAACTG GGAAATAAGG ATTCTTCTGC                      #AATTTGCTGA   240TCCTTGC TAAATATCGA CCTCACAATG CAGAGGATCT                      #TGTGGATGCT   300AGAAGGA AGAGGAAGAA AGGGAAACGA GGGGATATTT                      -  CTACTTTTCT TGGAA ATG CAA AAG ATT ATG CAT ATT - # TCT GTC CTC CTT TCT         351                                                                           #Met Gln Lys Ile Met His Ile Ser Val Leu L - #eu Ser                           #                10                                                            #TCT TCT AAC AGC ATA CAG     399TT GGT GTC                                     #Ser Ser Asn Ser Ile Gln Ile Phe Gly Val                                       #         25                                                                   #CAA GAA TAC AGT GCA TTT     447GC GCT GAT                                     #Gln Glu Tyr Ser Ala Phe Arg Gly Ala Asp                                       #     40                                                                       #GAG TTC AGA CTG ACA CCC     495CC ACT TCG                                     #Glu Phe Arg Leu Thr Pro Phe Ser Thr Ser                                       # 60                                                                           #TTC GCA GTC ACC AAT GCT     543CC AAC AGT                                     #Phe Ala Val Thr Asn Ala Val Ala Asn Ser                                       #                 75                                                           #GCA ATT TTT GGA TTT TAT     591GA GTC TAC                                     #Ala Ile Phe Gly Phe Tyr Arg Gly Val Tyr                                       #             90                                                               #TTC TGT GGG ACA CTC CAT     639TC ACA TCA                                     #Phe Cys Gly Thr Leu His Thr Ile Thr Ser                                       #         105                                                                  #GAT GGC ACA CAT CCA TTT     687TC CCA ACA                                     #Asp Gly Thr His Pro Phe Ser Phe Pro Thr                                       #    120                                                                       #GCA CTC CTT AGC TTG ATT     735TC AAA GGA                                     #Ala Leu Leu Ser Leu Ile Asp Leu Lys Gly                                       #140                                                                           #CTC TAT GAC AGT GAC AGA     783TC GCA TAC                                     #Leu Tyr Asp Ser Asp Arg Lys Phe Ala Tyr                                       #                155                                                           #TCT GCT GCA GAG AAG AAG     831TT CTG GAT                                     #Ser Ala Ala Glu Lys Lys Ala Val Leu Asp                                       #            170                                                               #ATC AAC AAT GAC AAG AAA     879TG GGG AAC                                     #Ile Asn Asn Asp Lys Lys Asn Val Gly Asn                                       #        185                                                                   #CTG GAG TTA AAA AAA GAA     927TT CAA GAT                                     #Leu Glu Leu Lys Lys Glu Leu Phe Gln Asp                                       #    200                                                                       #AAA GTA AAT GAC ATT GTG     975AA AGG GAT                                     #Lys Val Asn Asp Ile Val Cys Glu Arg Asp                                       #220                                                                           #AAA GGG TAC CAT TAT ATC    1023AA CAT GTT                                     #Lys Gly Tyr His Tyr Ile Gly Lys His Val                                       #                235                                                           #CTG CTG AAA ATT CAG TTT    1071AT GGG GAC                                     #Leu Leu Lys Ile Gln Phe Thr Asp Gly Asp                                       #            250                                                               #GTA GAC TAC GAC GAT TCC    1119TT CAG ATT                                     #Val Asp Tyr Asp Asp Ser Gly Phe Gln Ile                                       #        265                                                                   #ACA CTG GAA GAG AAA GAA    1167GA TGG TCA                                     #Thr Leu Glu Glu Lys Glu Glu Arg Trp Ser                                       #    280                                                                       #TAT ACT TCG GCC CTG ACG    1215CA ATT AAG                                     #Tyr Thr Ser Ala Leu Thr Ala Thr Ile Lys                                       #300                                                                           #TTC CGT AAC CTT CGG AAG    1263CT GAA GCA                                     #Phe Arg Asn Leu Arg Lys Met Thr Glu Ala                                       #                315                                                           #GCA GGG GAT TGT TTG GCC    1311GA GGA AAT                                     #Ala Gly Asp Cys Leu Ala Arg Arg Gly Asn                                       #            330                                                               #GAA ATA GAA AGG GCC CTC    1359AA GGG GTC                                     #Glu Ile Glu Arg Ala Leu Gly Gln Gly Val                                       #        345                                                                   #AAT ATA AAG TTT GAC CAG    1407TC TCT GGA                                     #Asn Ile Lys Phe Asp Gln Gly Leu Ser Gly                                       #    360                                                                       #ATC ATG GAG CTC AAA ACA    1455CA ATT AAC                                     #Ile Met Glu Leu Lys Thr Tyr Thr Ile Asn                                       #380                                                                           #GAA GTG GAT AAA ATG GTT    1503AC TGG AGT                                     #Glu Val Asp Lys Met Val Gly Tyr Trp Ser                                       #                395                                                           #GAC ACG TCT GGG CTT GAA    1551CA GGA AAT                                     #Asp Thr Ser Gly Leu Glu Pro Ser Gly Asn                                       #            410                                                               #GAA TCT CCA TAT GTT ATG    1599CA ATA TTG                                     #Glu Ser Pro Tyr Val Met Thr Thr Ile Leu                                       #        425                                                                   #AAT GAG CGT TAC GAG GGC    1647TT GAA GGG                                     #Asn Glu Arg Tyr Glu Gly Met Leu Glu Gly                                       #    440                                                                       #AAA CAC TGT GGG TTC AAG    1695AA ATT GCC                                     #Lys His Cys Gly Phe Lys Ala Glu Ile Ala                                       #460                                                                           #TAT GGG GCC AGG GAT GCC    1743AT GGC AAG                                     #Tyr Gly Ala Arg Asp Ala Gly Asp Gly Lys                                       #                475                                                           #GAG CTT GTC TAC GGG AAA    1791TG GTT GGA                                     #Glu Leu Val Tyr Gly Lys Gly Met Val Gly                                       #            490                                                               #ACT CTC GTG AGA GAA GAG    1839TA ACT ATC                                     #Thr Leu Val Arg Glu Glu Pro Leu Thr Ile                                       #        505                                                                   #CTT GGA ATC TCT ATC ATG    1887TC ATG AGT                                     #Leu Gly Ile Ser Ile Met Pro Phe Met Ser                                       #    520                                                                       #GTG TTT TCC TTT CTT GAT    1935AA CCA GGA                                     #Val Phe Ser Phe Leu Asp Ser Lys Pro Gly                                       #540                                                                           #GTG TTT GCC TAC ATT GGG    1983TG TGC ATT                                     #Val Phe Ala Tyr Ile Gly Trp Met Cys Ile                                       #                555                                                           #TTT AGC CCC TAC GAG TGG    2031TC AGC AGA                                     #Phe Ser Pro Tyr Glu Trp Leu Val Ser Arg                                       #            570                                                               #ACA CAA AGT AGT GAA TCA    2079GA AGA GAA                                     #Thr Gln Ser Ser Glu Ser Asp Gly Arg Glu                                       #        585                                                                   #TGG TTT TCC TTG GGT GCC    2127AT AGT CTC                                     #Trp Phe Ser Leu Gly Ala Phe Asn Ser Leu                                       #    600                                                                       #AGA TCC CTC TCT GGG CGC    2175TT TCG CCA                                     #Arg Ser Leu Ser Gly Arg Asp Ile Ser Pro                                       #620                                                                           #CTG ATC ATA ATC TCC TCC    2223TC TTT ACC                                     #Leu Ile Ile Ile Ser Ser Trp Phe Phe Thr                                       #                635                                                           #GTA GAG AGG ATG GTG TCT    2271TC CTG ACT                                     #Val Glu Arg Met Val Ser Ala Phe Leu Thr                                       #            650                                                               #CAA ACA GAA ATT GCT TAT    2319TG TCT AAG                                     #Gln Thr Glu Ile Ala Tyr Asp Leu Ser Lys                                       #        665                                                                   #TTT TTC AGG AGA TCT AAA    2367CT AAA GAG                                     #Phe Phe Arg Arg Ser Lys Ser Thr Lys Glu                                       #    680                                                                       #ATG AGG AGT GCA GAG CCC    2415GG ACT TAT                                     #Met Arg Ser Ala Glu Pro Met Trp Thr Tyr                                       #700                                                                           #GTA GCC AGA GTC CGG AAA    2463CA GAA GGA                                     #Val Ala Arg Val Arg Lys Thr Ala Glu Gly                                       #                715                                                           #TCC ACA ATG AAC GAG TAC    2511TG CTG GAG                                     #Ser Thr Met Asn Glu Tyr Tyr Leu Leu Glu                                       #            730                                                               #AAA GTG GGA GGA AAC TTG    2559AC ACC ATG                                     #Lys Val Gly Gly Asn Leu Cys Asp Thr Met                                       #        745                                                                   #AAA GGA TCC TCA TTA GGA    2607CC ACA CCT                                     #Lys Gly Ser Ser Leu Gly Ile Ala Thr Pro                                       #    760                                                                       #AAT GAA CAA GGC CTG TTG    2655TA AAA CTG                                     #Asn Glu Gln Gly Leu Leu Val Leu Lys Leu                                       #780                                                                           #AAA GGA GAG TGC GGC AGC    2703GG TAC GAC                                     #Lys Gly Glu Cys Gly Ser Trp Trp Tyr Asp                                       #                795                                                           #GCC CTC AGT CTG AGC AAC    2751AG ACC AGT                                     #Ala Leu Ser Leu Ser Asn Glu Lys Thr Ser                                       #            810                                                               #GGC CTT GGT TTG GCA ATG    2799TT GTC GGG                                     #Gly Leu Gly Leu Ala Met Ile Leu Val Gly                                       #        825                                                                   #TCA AGG GCC GAG GCG AAA    2847GT TAC AAG                                     #Ser Arg Ala Glu Ala Lys Phe Cys Tyr Lys                                       #    840                                                                       #ATT AAC CCA TCT TCC TCG    2895CA CAG AAT                                     #Ile Asn Pro Ser Ser Ser Asn Pro Gln Asn                                       #860                                                                           #GAA GGT TAC AAC GTA TAT    2943CT TAT AAG                                     #Glu Gly Tyr Asn Val Tyr Ala Thr Tyr Lys                                       #                875                                                           -  GGC ATC GAG AGT GTT AAA ATT TAGGGGATGA CCTTG - #AGTGA TGTCATGAGG AGCA       2998                                                                            Gly Ile Glu Ser Val Lys Ile                                                                880                                                               #ACTCCAGAAT  3058AATTACA GGAAGTACTG GAGAAAATGG ACGTGTTATG                      #AATGTCAGTG  3118GCATGCT GTCCCTTACG TGAGTCCTGG CATGGGAATG                      #GTTTCCTTGT  3178GTGATTG ATAGGAACCT TCTGAGTGCC TTACACAATG                      #TTTCAGCCAA  3238AAGTGGT GAGAGGCATC CGATATCTTG AAGGCTTTTC                      #ACAAACAGAG  3298TGTGGAG TTCACCTTGA ATTGTAAGGA AAGATAAATT                      #AACATGGAAA  3358TCCGATA TCAGAGGAAG CGTGGTGGAC ATGCACAGCT                      #GCCACTATTG  3418CTGAAGT CTTTGTACAG ACAACAAACC CGTTTCCGCA                      #AAGATGTGAC  3478TCATAAT GACTTAAGCA CACTTGACAT CAACTGCATC                      #           3505   AAAAA AAAAAAA                                               - (2) INFORMATION FOR SEQ ID NO:4:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 883 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:                                  #Leu Ser Pro Val Leu Trpis Ile Ser Val Leu                                     #                 15                                                           #Ile Gln Ile Gly Gly Leual Ser Ser Asn Ser                                     #             30                                                               #Ala Phe Arg Val Gly Metsp Gln Glu Tyr Ser                                     #         45                                                                   #Thr Pro His Ile Asp Asner Glu Phe Arg Leu                                     #     60                                                                       #Asn Ala Phe Cys Ser Glner Phe Ala Val Thr                                     # 80                                                                           #Phe Tyr Asp Lys Lys Seryr Ala Ile Phe Gly                                     #                 95                                                           #Leu His Val Ser Phe Ileer Phe Cys Gly Thr                                     #            110                                                               #Pro Phe Val Ile Gln Methr Asp Gly Thr His                                     #        125                                                                   #Leu Ile Glu Tyr Tyr Glnly Ala Leu Leu Ser                                     #    140                                                                       #Asp Arg Gly Leu Ser Thryr Leu Tyr Asp Ser                                     #160                                                                           #Lys Lys Trp Gln Val Thrsp Ser Ala Ala Glu                                     #                175                                                           #Lys Lys Asp Glu Thr Tyrsn Ile Asn Asn Asp                                     #            190                                                               #Lys Glu Arg Arg Val Ilesp Leu Glu Leu Lys                                     #        205                                                                   #Ile Val Asp Gln Val Ilesp Lys Val Asn Asp                                     #    220                                                                       #Tyr Ile Ile Ala Asn Leual Lys Gly Tyr His                                     #240                                                                           #Gln Phe Gly Gly Ala Asnsp Leu Leu Lys Ile                                     #                255                                                           #Asp Ser Leu Val Ser Lysle Val Asp Tyr Asp                                     #            270                                                               #Lys Glu Tyr Pro Gly Alaer Thr Leu Glu Glu                                     #        285                                                                   #Leu Thr Tyr Asp Ala Valys Tyr Thr Ser Ala                                     #    300                                                                       #Arg Lys Gln Arg Ile Glula Phe Arg Asn Leu                                     #320                                                                           #Leu Ala Asn Pro Ala Valsn Ala Gly Asp Cys                                     #                335                                                           #Ala Leu Lys Gln Val Glnal Glu Ile Glu Arg                                     #            350                                                               #Asp Gln Asn Gly Lys Argly Asn Ile Lys Phe                                     #        365                                                                   #Lys Thr Asn Gly Pro Argsn Ile Met Glu Leu                                     #    380                                                                       #Met Val Val Thr Leu Threr Glu Val Asp Lys                                     #400                                                                           #Leu Glu Asn Lys Thr Valsn Asp Thr Ser Gly                                     #                415                                                           #Val Met Met Lys Lys Asneu Glu Ser Pro Tyr                                     #            430                                                               #Glu Gly Tyr Cys Val Asply Asn Glu Arg Tyr                                     #        445                                                                   #Phe Lys Tyr Lys Leu Thrla Lys His Cys Gly                                     #    460                                                                       #Asp Ala Asp Thr Lys Ileys Tyr Gly Ala Arg                                     #480                                                                           #Gly Lys Ala Asp Ile Alaly Glu Leu Val Tyr                                     #                495                                                           #Glu Glu Val Ile Asp Phele Thr Leu Val Arg                                     #            510                                                               #Ile Met Ile Lys Lys Proer Leu Gly Ile Ser                                     #        525                                                                   #Leu Asp Pro Leu Ala Tyrly Val Phe Ser Phe                                     #    540                                                                       #Ile Gly Val Ser Val Valle Val Phe Ala Tyr                                     #560                                                                           #Glu Trp His Thr Glu Glurg Phe Ser Pro Tyr                                     #                575                                                           #Glu Ser Thr Asn Glu Phelu Thr Gln Ser Ser                                     #            590                                                               #Gly Ala Phe Met Arg Glneu Trp Phe Ser Leu                                     #        605                                                                   #Gly Arg Ile Val Gly Glyro Arg Ser Leu Ser                                     #    620                                                                       #Ser Ser Tyr Thr Ala Asnhr Leu Ile Ile Ile                                     #640                                                                           #Val Ser Pro Ile Glu Serhr Val Glu Arg Met                                     #                655                                                           #Ala Tyr Gly Thr Leu Aspys Gln Thr Glu Ile                                     #            670                                                               #Ser Lys Ile Ala Val Phelu Phe Phe Arg Arg                                     #        685                                                                   #Glu Pro Ser Val Phe Valyr Met Arg Ser Ala                                     #    700                                                                       #Arg Lys Ser Lys Gly Lysly Val Ala Arg Val                                     #720                                                                           #Glu Tyr Ile Glu Gln Arglu Ser Thr Met Asn                                     #                735                                                           #Asn Leu Asp Ser Lys Glyet Lys Val Gly Gly                                     #            750                                                               #Leu Gly Asn Ala Val Asnro Lys Gly Ser Ser                                     #        765                                                                   #Leu Leu Asp Lys Leu Lyseu Asn Glu Gln Gly                                     #    780                                                                       #Gly Ser Gly Gly Gly Aspsp Lys Gly Glu Cys                                     #800                                                                           #Ser Asn Val Ala Gly Valer Ala Leu Ser Leu                                     #                815                                                           #Ala Met Leu Val Ala Leuly Gly Leu Gly Leu                                     #            830                                                               #Ala Lys Arg Met Lys Valys Ser Arg Ala Glu                                     #        845                                                                   #Ser Ser Gln Asn Ser Glnsn Ile Asn Pro Ser                                     #    860                                                                       #Val Tyr Gly Ile Glu Serys Glu Gly Tyr Asn                                     #880                                                                           -  Val Lys Ile                                                                 - (2) INFORMATION FOR SEQ ID NO:5:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 3083 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR3                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 167...2830                                                       (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:5:                                  #TTCTCTCAGA    60CTCTCTC TCTCTCTCTC TCTCTCTCTC TCTCTCTCTC                      #GGTGTGAAGA   120AACCCAG CTTGCAGCCA ATGAACCCGC CTTCCAGATT                      -  CAGAAGTGAG CTTCGTTTTA GGCGTCAAGC AGCCAGGCAG AAGAAA AT - #G GGG CAA           175                                                                           #Gly Gln         Met                                                           #                 1                                                            #CTG GGG CTT TTG GGT CAT     223TT TTA GTC                                     #Leu Gly Leu Leu Gly His Phe Phe Leu Val                                       #      15                                                                      #ATA GGT GGA CTT TTC ATG     271CC ATC AGC                                     #Ile Gly Gly Leu Phe Met Asn Thr Ile Ser                                       # 35                                                                           #CGC TTT GCT GTG CAG TTA     319GC GCT TTC                                     #Arg Phe Ala Val Gln Leu His Ser Ala Phe                                       #                 50                                                           #CCC TTC CAT TTG AAT TAC     367CT GAG AAG                                     #Pro Phe His Leu Asn Tyr Thr Thr Glu Lys                                       #             65                                                               #TTT TCT GTG ACT AAT GCT     415CC AAT AGT                                     #Phe Ser Val Thr Asn Ala Ser Ser Asn Ser                                       #         80                                                                   #GCT ATC TTT GGA TTC TAT     463GG GTG TAT                                     #Ala Ile Phe Gly Phe Tyr Arg Gly Val Tyr                                       #     95                                                                       #TTC TGT GGG GCC CTG CAC     511TG ACC TCC                                     #Phe Cys Gly Ala Leu His Thr Leu Thr Ser                                       #115                                                                           #GAT GCA GAT GTG CAG TTT     559TT CCC ACT                                     #Asp Ala Asp Val Gln Phe Ser Phe Pro Thr                                       #                130                                                           #GCC ATT CTG AGT CTT CTC     607TG AAG GGT                                     #Ala Ile Leu Ser Leu Leu Ala Leu Lys Gly                                       #            145                                                               #CTC TAT GAC ACA GAA CGA     655TT GTG TAC                                     #Leu Tyr Asp Thr Glu Arg Lys Phe Val Tyr                                       #        160                                                                   #GCA GCA GTG CAA AAC AAC     703TT ATG GAG                                     #Ala Ala Val Gln Asn Asn Ala Ile Met Glu                                       #    175                                                                       #ATA AAG GAC GTC CAG GAA     751TG GGA AAC                                     #Ile Lys Asp Val Gln Glu Ser Val Gly Asn                                       #195                                                                           #AGG CAG GAA AAA CGA TAC     799TG GAC AGA                                     #Arg Gln Glu Lys Arg Tyr Glu Met Asp Arg                                       #                210                                                           #ACA ATT TTG GAA CAG GTT     847GG ATT AAC                                     #Thr Ile Leu Glu Gln Val Glu Arg Ile Asn                                       #            225                                                               #CAC TAC ATG CTT GCT AAC     895GA GGC TAT                                     #His Tyr Met Leu Ala Asn Ser Arg Gly Tyr                                       #        240                                                                   #GTC ATG CAT GGG GGA GCC     943TG GAA AGA                                     #Val Met His Gly Gly Ala Leu Leu Glu Arg                                       #    255                                                                       #GAA AAC CCA ATG GTT CAG     991TC AAC AAT                                     #Glu Asn Pro Met Val Gln Ile Val Asn Asn                                       #275                                                                           #GAA AGG GAA TTC CCT GAA    1039GA CTG GAT                                     #Glu Arg Glu Phe Pro Glu Val Arg Leu Asp                                       #                290                                                           #GCG CTG ACA CAT GAC GCA    1087AT ACA TCT                                     #Ala Leu Thr His Asp Ala Lys Tyr Thr Ser                                       #            305                                                               #CTG AGG AGA CAG AGA GTG    1135TC CGA TAC                                     #Leu Arg Arg Gln Arg Val Ala Phe Arg Tyr                                       #        320                                                                   #TGC TTA GCA AAT CCT GCT    1183CT GGA GAC                                     #Cys Leu Ala Asn Pro Ala Ser Ala Gly Asp                                       #    335                                                                       #AGA GCT CTG AAA ATG GTG    1231AT ATT GAG                                     #Arg Ala Leu Lys Met Val Ile Asp Ile Glu                                       #355                                                                           #TTT GAC ACT TAT GGA CGT    1279AC ATC CAA                                     #Phe Asp Thr Tyr Gly Arg Gly Asn Ile Gln                                       #                370                                                           #ATG AAA GTC TCG GGT TCT    1327TC TAT GAA                                     #Met Lys Val Ser Gly Ser Asp Val Tyr Glu                                       #            385                                                               #AGG TTT GTG CCC TTC TCA    1375AA TAT GAA                                     #Arg Phe Val Pro Phe Ser Asn Glu Tyr Glu                                       #        400                                                                   #TCA GAG AAC CGG ACC ATT    1423GC TCA TCC                                     #Ser Glu Asn Arg Thr Ile Asp Ser Ser Ser                                       #    415                                                                       #GTG ATG TAT AAA AAG AAT    1471CA CCA TAT                                     #Val Met Tyr Lys Lys Asn Glu Ser Pro Tyr                                       #435                                                                           #GAA GGC TAC TGT GTT GAT    1519AG CGC TAT                                     #Glu Gly Tyr Cys Val Asp Asn Glu Arg Tyr                                       #                450                                                           #ATC AAA TAC AAA TTG TCC    1567AC GTA AGG                                     #Ile Lys Tyr Lys Leu Ser Lys His Val Arg                                       #            465                                                               #GAT CCA GAG ACT AAA ATA    1615GC GCC AGA                                     #Asp Pro Glu Thr Lys Ile Tyr Gly Ala Arg                                       #        480                                                                   #GGA AGA GCT GAT ATA GCT    1663TT GTC TAT                                     #Gly Arg Ala Asp Ile Ala Glu Leu Val Tyr                                       #    495                                                                       #GAA GAA GTC ATA GAT TTC    1711TG GTC CGT                                     #Glu Glu Val Ile Asp Phe Thr Leu Val Arg                                       #515                                                                           #ATC ATG ATA AAG AAG CCT    1759GA ATC TCC                                     #Ile Met Ile Lys Lys Pro Leu Gly Ile Ser                                       #                530                                                           #CTG GAT CCT TTG GCT TAT    1807TT TCA TTC                                     #Leu Asp Pro Leu Ala Tyr Val Phe Ser Phe                                       #            545                                                               #ATT GGA GTC AGT GTA GTT    1855TC GCT TAC                                     #Ile Gly Val Ser Val Val Val Phe Ala Tyr                                       #        560                                                                   #GAA TGG CAC TTG GAA GAC    1903GC CCT TAT                                     #Glu Trp His Leu Glu Asp Phe Ser Pro Tyr                                       #    575                                                                       #CCT CCT GAT CCT CCC AAT    1951CA CAA AGC                                     #Pro Pro Asp Pro Pro Asn Asp Pro Gln Ser                                       #595                                                                           #TCC TTG GGT GCT TTC ATG    1999TT TGG TTT                                     #Ser Leu Gly Ala Phe Met Ser Leu Trp Phe                                       #                610                                                           #CTT TCT GGG CGC ATT GTT    2047CA AGA TCA                                     #Leu Ser Gly Arg Ile Val Ser Pro Arg Ser                                       #            625                                                               #ATA ATC TCT TCC TAC ACT    2095CC CTG ATC                                     #Ile Ile Ser Ser Tyr Thr Phe Thr Leu Ile                                       #        640                                                                   #AGG ATG GTG TCC CCT ATA    2143CT GTG GAG                                     #Arg Met Val Ser Pro Ile Leu Thr Val Glu                                       #    655                                                                       #GAA ATT GCA TAT GGG ACC    2191AG CAG ACT                                     #Glu Ile Ala Tyr Gly Thr Ala Lys Gln Thr                                       #675                                                                           #AGA CGA TCC AAA ATT GCT    2239AA TTT TTC                                     #Arg Arg Ser Lys Ile Ala Lys Glu Phe Phe                                       #                690                                                           #TCC GCA GAG CCA TCT GTG    2287AC ATG AAA                                     #Ser Ala Glu Pro Ser Val Ser Tyr Met Lys                                       #            705                                                               #CGA GTT CGG AAG TCC AAG    2335GG GTA GCC                                     #Arg Val Arg Lys Ser Lys Asp Gly Val Ala                                       #        720                                                                   #ATG AAC GAG TAC ATT GAG    2383AG TCG ACC                                     #Met Asn Glu Tyr Ile Glu Leu Glu Ser Thr                                       #    735                                                                       #GGT GGA AAT CTG GAT TCC    2431TG AAA GTT                                     #Gly Gly Asn Leu Asp Ser Thr Met Lys Val                                       #755                                                                           #TCA GCA TTA GGA AAT GCT    2479CT AAA GGC                                     #Ser Ala Leu Gly Asn Ala Thr Pro Lys Gly                                       #                770                                                           #CAA GGC CTC TTG GAC AAA    2527TG AAT GAG                                     #Gln Gly Leu Leu Asp Lys Lys Leu Asn Glu                                       #            785                                                               #GAG TGC GGC AGC GGG GGC    2575AC AAA GGA                                     #Glu Cys Gly Ser Gly Gly Tyr Asp Lys Gly                                       #        800                                                                   #AGC CTG AGC AAT GTG GCA    2623GT GCT CTA                                     #Ser Leu Ser Asn Val Ala Thr Ser Ala Leu                                       #    815                                                                       #GGC CTG GCC ATG ATG GTG    2671GA GGT CTG                                     #Gly Leu Ala Met Met Val Val Gly Gly Leu                                       #835                                                                           #GCA GAG TCC AAA CGC ATG    2719AA TCA CGG                                     #Ala Glu Ser Lys Arg Met Tyr Lys Ser Arg                                       #                850                                                           #CCT GCT CCT GCC ACC AAC    2767AC TTT AAG                                     #Pro Ala Pro Ala Thr Asn Gln Asn Phe Lys                                       #            865                                                               #TAC AAC GTG TAT GGA ACA    2815GA GAA GGC                                     #Tyr Asn Val Tyr Gly Thr Tyr Arg Glu Gly                                       #        880                                                                   -  GAA AGT GTT AAG ATC TAGGGATCCC TTCCCACCAG AAGCA - #TGCAA TGAGAGGAAA T       2871                                                                            Glu Ser Val Lys Ile                                                                885                                                                       #TGGTGTCGGG  2931GCTGCTT CAAGGATCCT GAGCCGGATT TCACTCTCCC                      #GATTTTTTTT  2991TTGCTGA TGGTGCAATG ACCTTTCAAT AGGAAAAACT                      #TCATTGAAAT  3051TTATGGA ACACTCTGAG ACTTGCGACA ATGCAAACCA                      #        3083      GAAAA AAAAAAAAAA AA                                         - (2) INFORMATION FOR SEQ ID NO:6:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 888 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:6:                                  #Phe Leu Val Leu Gly Leueu Arg Ala Val Phe                                     #                 15                                                           #Thr Ile Ser Ile Gly Glyly Gly Phe Pro Asn                                     #             30                                                               #Ser Ala Phe Arg Phe Alahr Val Gln Glu His                                     #         45                                                                   #Thr Glu Lys Pro Phe Hishr Asn Gln Asn Thr                                     #     60                                                                       #Ser Asn Ser Phe Ser Valsp His Leu Asp Ser                                     # 80                                                                           #Gly Val Tyr Ala Ile Pheer Gln Phe Ser Arg                                     #                 95                                                           #Leu Thr Ser Phe Cys Glyet Ser Met Asn Thr                                     #            110                                                               #Phe Pro Thr Asp Ala Asphe Val Thr Pro Ser                                     #        125                                                                   #Leu Lys Gly Ala Ile Leuln Met Arg Pro Ala                                     #    140                                                                       #Phe Val Tyr Leu Tyr Aspyr Lys Trp Glu Lys                                     #160                                                                           #Ile Met Glu Ala Ala Valer Val Leu Gln Ala                                     #                175                                                           #Val Gly Asn Ile Lys Aspal Thr Ala Arg Ser                                     #            190                                                               #Met Asp Arg Arg Gln Glurg Ile Ile Glu Glu                                     #        205                                                                   #Arg Ile Asn Thr Ile Leusp Cys Glu Val Glu                                     #    220                                                                       #Arg Gly Tyr His Tyr Meteu Gly Lys His Ser                                     #240                                                                           #Leu Glu Arg Val Met Hishe Thr Asp Ile Leu                                     #                255                                                           #Val Asn Asn Glu Asn Prohr Gly Phe Gln Ile                                     #            270                                                               #Arg Leu Asp Glu Arg Glule Gln Arg Trp Val                                     #        285                                                                   #Tyr Thr Ser Ala Leu Thrsn Ala Pro Leu Lys                                     #    300                                                                       #Phe Arg Tyr Leu Arg Argal Ile Ala Glu Ala                                     #320                                                                           #Ala Gly Asp Cys Leu Alaer Arg Arg Gly Ser                                     #                335                                                           #Asp Ile Glu Arg Ala Leurp Ser Gln Gly Ile                                     #            350                                                               #Asn Ile Gln Phe Asp Thrln Gly Met Thr Gly                                     #        365                                                                   #Val Tyr Glu Met Lys Valsn Tyr Thr Ile Asp                                     #    380                                                                       #Glu Tyr Glu Arg Phe Valla Gly Tyr Trp Asn                                     #400                                                                           #Ser Ser Ser Ser Glu Asnln Ile Ser Asn Asp                                     #                415                                                           #Ser Pro Tyr Val Met Tyrhr Thr Ile Leu Glu                                     #            430                                                               #Glu Arg Tyr Glu Gly Tyrln Leu Glu Gly Asn                                     #        445                                                                   #His Val Arg Ile Lys Tyryr Glu Ile Ala Lys                                     #    460                                                                       #Gly Ala Arg Asp Pro Gluly Asp Gly Lys Tyr                                     #480                                                                           #Leu Val Tyr Gly Arg Alaly Met Val Gly Glu                                     #                495                                                           #Leu Val Arg Glu Glu Valro Leu Thr Ile Thr                                     #            510                                                               #Gly Ile Ser Ile Met Ilela Phe Met Ser Leu                                     #        525                                                                   #Phe Ser Phe Leu Asp Proer Lys Pro Gly Val                                     #    540                                                                       #Phe Ala Tyr Ile Gly Valrp Met Cys Ile Val                                     #560                                                                           #Ser Pro Tyr Glu Trp Hiseu Val Ser Arg Phe                                     #                575                                                           #Pro Gln Ser Pro Pro Asplu Glu Pro Arg Asp                                     #            590                                                               #Leu Trp Phe Ser Leu Glyly Ile Phe Asn Ser                                     #        605                                                                   #Pro Arg Ser Leu Ser Glyly Cys Asp Ile Ser                                     #    620                                                                       #Thr Leu Ile Ile Ile Seral Trp Trp Phe Phe                                     #640                                                                           #Thr Val Glu Arg Met Valeu Ala Ala Phe Leu                                     #                655                                                           #Lys Gln Thr Glu Ile Alala Glu Asp Leu Ala                                     #            670                                                               #Glu Phe Phe Arg Arg Serer Gly Ser Thr Lys                                     #        685                                                                   #Tyr Met Lys Ser Ala Glulu Lys Met Trp Ser                                     #    700                                                                       #Gly Val Ala Arg Val Argys Thr Thr Ala Asp                                     #720                                                                           #Glu Ser Thr Met Asn Gluhe Ala Phe Leu Leu                                     #                735                                                           #Met Lys Val Gly Gly Asnys Pro Cys Asp Thr                                     #            750                                                               #Pro Lys Gly Ser Ala Leuyr Gly Val Ala Thr                                     #        765                                                                   #Leu Asn Glu Gln Gly Leueu Ala Val Leu Lys                                     #    780                                                                       #Asp Lys Gly Glu Cys Glysn Lys Trp Trp Tyr                                     #800                                                                           #Ser Ala Leu Ser Leu Serer Lys Asp Lys Thr                                     #                815                                                           #Gly Gly Leu Gly Leu Alahe Tyr Ile Leu Val                                     #            830                                                               #Lys Ser Arg Ala Glu Serle Glu Phe Cys Tyr                                     #        845                                                                   #Asn Phe Lys Pro Ala Prohr Lys Asn Thr Gln                                     #    860                                                                       #Arg Glu Gly Tyr Asn Valsn Tyr Ala Thr Tyr                                     #880                                                                           -  Tyr Gly Thr Glu Ser Val Lys Ile                                                              885                                                           - (2) INFORMATION FOR SEQ ID NO:7:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 2971 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR4                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 162...2867                                                       (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:7:                                  #CCCAGAAAAC    60CGCAAAA TCCTCTGTCT GTGGACTCGC ACCAGAGCCT                      #AAGACTGAGA   120GCCATCG TCTTCAATGC CTCTCTGAAA AGCCTTTAGC                      #AGG ATT ATT TGC   176CG CCAGAGAGAG GAGCAAAGAA G ATG                           #Cys        Met Arg Ile Ile                                                    #         5  1                                                                 #TGG GGA CTC GCC ATG GGA     224CT GGA TTT                                     #Trp Gly Leu Ala Met Gly Phe Ser Gly Phe                                       #                 20                                                           #CTC TTC ATC CGA AAC ACA     272TA GGT GGT                                     #Leu Phe Ile Arg Asn Thr Gln Ile Gly Gly                                       #             35                                                               #ATC TTT CTT CAT AAC ACC     320GA CTG GCA                                     #Ile Phe Leu His Asn Thr Phe Arg Leu Ala                                       #         50                                                                   #TTG GTA CCT CAT GTG GAC     368CT TTC AAT                                     #Leu Val Pro His Val Asp Ala Pro Phe Asn                                       #     65                                                                       #ACA AAC GCC TTC TGT TCC     416TT GCT GTG                                     #Thr Asn Ala Phe Cys Ser Ser Phe Ala Val                                       # 85                                                                           #GGA CTC TAT GAC AAG AGA     464CC ATT TTT                                     #Gly Leu Tyr Asp Lys Arg Phe Ala Ile Phe                                       #                 100                                                          #CGT CTG CAC ATC TCT CTC     512TC TGC AGG                                     #Arg Leu His Ile Ser Leu Ser Phe Cys Arg                                       #            115                                                               #AGC CAG TTT GTG CTG CAG     560AA GGG GAG                                     #Ser Gln Phe Val Leu Gln Thr Glu Gly Glu                                       #        130                                                                   #AGC CTC CTG GAT CAC TAT     608CA CTC CTG                                     #Ser Leu Leu Asp His Tyr Gly Ala Leu Leu                                       #    145                                                                       #ACA GAC AGG GGG TAT TCA     656TG TAT GAT                                     #Thr Asp Arg Gly Tyr Ser Phe Leu Tyr Asp                                       #165                                                                           #CAA AAT GGA TGG CAT GTC     704AA GCA GGA                                     #Gln Asn Gly Trp His Val Glu Lys Ala Gly                                       #                180                                                           #GTC AGC TAC AGG CAA CTG     752TT AAT GAT                                     #Val Ser Tyr Arg Gln Leu Asn Phe Asn Asp                                       #            195                                                               #AAA TTT GTG ATA GAT TGT     800AA GAG AAG                                     #Lys Phe Val Ile Asp Cys Arg Gln Glu Lys                                       #        210                                                                   #CAA ATT GTG AGT GTT GGG     848TT TTA GAA                                     #Gln Ile Val Ser Val Gly Asn Ile Leu Glu                                       #    225                                                                       #GCA AAT TTG GGT TTC AAG     896AT ATC ATC                                     #Ala Asn Leu Gly Phe Lys His Tyr Ile Ile                                       #245                                                                           #GGA GCA AAT GTA ACA GGA     944TA CAT GGA                                     #Gly Ala Asn Val Thr Gly Phe Ile His Gly                                       #                260                                                           #GTA ACC AAA CTA ATG GAT     992CA CCC ATG                                     #Val Thr Lys Leu Met Asp Asn Thr Pro Met                                       #            275                                                               #CCA GGT TCT GAA ACA CCT    1040GA GAA TAT                                     #Pro Gly Ser Glu Thr Pro Gln Arg Glu Tyr                                       #        290                                                                   #GGA GTC CTG GTG ATG GCT    1088CT TAT GAT                                     #Gly Val Leu Val Met Ala Leu Thr Tyr Asp                                       #    305                                                                       #ATT GAT ATT TCA AGG AGA    1136GA CAG AAA                                     #Ile Asp Ile Ser Arg Arg Arg Arg Gln Lys                                       #325                                                                           #GCT GCT CCC TGG GGC CAG    1184CA AAC CCT                                     #Ala Ala Pro Trp Gly Gln Leu Ala Asn Pro                                       #                340                                                           #GTT CGA ATT CAA GGG CTG    1232TG AAG CAG                                     #Val Arg Ile Gln Gly Leu Thr Leu Lys Gln                                       #            355                                                               #CGT AGA GTT AAT TAC ACA    1280AT TAT GGA                                     #Arg Arg Val Asn Tyr Thr Asp His Tyr Gly                                       #        370                                                                   #CCT CGA AAG GTT GGC TAC    1328GC ACA GGA                                     #Pro Arg Lys Val Gly Tyr Lys Ser Thr Gly                                       #    385                                                                       #CAA GAT ATG CCT ACT CTG    1376TC TTG ATT                                     #Gln Asp Met Pro Thr Leu Leu Val Leu Ile                                       #405                                                                           #ACA GTG GTT GTA ACC ACA    1424AG AAC AGA                                     #Thr Val Val Val Thr Thr Ile Glu Asn Arg                                       #                420                                                           #AAA AAT CAT GAA ATG TTT    1472TG TAC AAG                                     #Lys Asn His Glu Met Phe Val Met Tyr Lys                                       #            435                                                               #GTA GAT CTG GCA TCG GAA    1520GC TAC TGT                                     #Val Asp Leu Ala Ser Glu Glu Gly Tyr Cys                                       #        450                                                                   #ATT GCC ATT GTT CCT GAT    1568AA TAT AAA                                     #Ile Ala Ile Val Pro Asp Ile Lys Tyr Lys                                       #    465                                                                       #AAG ATC TGG AAT GGG ATG    1616CA GAC ACT                                     #Lys Ile Trp Asn Gly Met Asp Ala Asp Thr                                       #485                                                                           #ATT GCT ATT GCC CCT CTG    1664AA GCA GAG                                     #Ile Ala Ile Ala Pro Leu Gly Lys Ala Glu                                       #                500                                                           #GAT TTT TCT AAG CCT TTT    1712AA GTC ATC                                     #Asp Phe Ser Lys Pro Phe Glu Glu Val Ile                                       #            515                                                               #AAA CCT CAG AAA TCT AAA    1760TG ATC AAA                                     #Lys Pro Gln Lys Ser Lys Ile Met Ile Lys                                       #        530                                                                   #GCC TAT GAG ATC TGG ATG    1808AC CCT CTG                                     #Ala Tyr Glu Ile Trp Met Leu Asp Pro Leu                                       #    545                                                                       #GTG GTC TTG TTC CTA GTC    1856GT GTC AGT                                     #Val Val Leu Phe Leu Val Ile Gly Val Ser                                       #565                                                                           #GAA GAA CCT GAG GAT GGG    1904GG CAC ACA                                     #Glu Glu Pro Glu Asp Gly Glu Trp His Thr                                       #                580                                                           #GAA TTT GGC ATC TTT AAC    1952CT CCC AAT                                     #Glu Phe Gly Ile Phe Asn Gln Pro Pro Asn                                       #            595                                                               #CAA CAA GGA TGT GAC ATT    2000CC TTT ATG                                     #Gln Gln Gly Cys Asp Ile Gly Ala Phe Met                                       #        610                                                                   #GGA GGC GTG TGG TGG TTC    2048GG ATT GTT                                     #Gly Gly Val Trp Trp Phe Gly Arg Ile Val                                       #    625                                                                       #GCT AAT CTG GCT GCA TTC    2096CC TAC ACT                                     #Ala Asn Leu Ala Ala Phe Ser Ser Tyr Thr                                       #645                                                                           #GAA AGT GCA GAA GAC CTG    2144CC CCC ATA                                     #Glu Ser Ala Glu Asp Leu Val Ser Pro Ile                                       #                660                                                           #CTT GAT TCT GGG TCA ACA    2192AT GGA ACA                                     #Leu Asp Ser Gly Ser Thr Ala Tyr Gly Thr                                       #            675                                                               #GTG TAT GAA AAG ATG TGG    2240AA ATA GCA                                     #Val Tyr Glu Lys Met Trp Ser Lys Ile Ala                                       #        690                                                                   #TTC ACT AGA ACT ACA GCT    2288CG TCT GTG                                     #Phe Thr Arg Thr Thr Ala Glu Pro Ser Val                                       #    705                                                                       #GGC AAA TTT GCC TTT CTC    2336AG TCC AAG                                     #Gly Lys Phe Ala Phe Leu Arg Lys Ser Lys                                       #725                                                                           #CAG CGA AAG CCC TGT GAC    2384AC ATT GAG                                     #Gln Arg Lys Pro Cys Asp Glu Tyr Ile Glu                                       #                740                                                           #AAA GGC TAT GGT GTA GCA    2432TG GAT TCC                                     #Lys Gly Tyr Gly Val Ala Asn Leu Asp Ser                                       #            755                                                               #GTA AAC CTT GCC GTT TTG    2480GA ACT CCT                                     #Val Asn Leu Ala Val Leu Leu Arg Thr Pro                                       #        770                                                                   #CTG AAA AAC AAA TGG TGG    2528TA GAC AAG                                     #Leu Lys Asn Lys Trp Trp Val Leu Asp Lys                                       #    785                                                                       #TCG GGA AGC AAG GAC AAG    2576CC AAG GAC                                     #Ser Gly Ser Lys Asp Lys Gly Pro Lys Asp                                       #805                                                                           #GGC GTC TTC TAC ATT CTG    2624AC GTA GCA                                     #Gly Val Phe Tyr Ile Leu Ser Asn Val Ala                                       #                820                                                           #GCT TTG ATA GAG TTC TGT    2672TG CTG GTG                                     #Ala Leu Ile Glu Phe Cys Ala Met Leu Val                                       #            835                                                               #AAG CTG ACT TTT TCC GAA    2720AG AGA ATG                                     #Lys Leu Thr Phe Ser Glu Ala Lys Arg Met                                       #        850                                                                   #ACT GGG AGT GTG GGA GAA    2768TA TCC ATC                                     #Thr Gly Ser Val Gly Glu Arg Leu Ser Ile                                       #    865                                                                       #AAG GCC GTA CAC ACA GGA    2816AC TGC CCC                                     #Lys Ala Val His Thr Gly Pro Asp Cys Pro                                       #885                                                                           #GTC ATT GCA TCG GAC CTA    2864GA TTG GCT                                     #Val Ile Ala Ser Asp Leu Ser Gly Leu Ala                                       #                900                                                           -  CCA TAAAAACCAA AAAAATAATT GAGTGCCTTA ATCAAACTGT GTTGG - #TGACT GACTGA       2923                                                                            Pro                                                                           #              2971GAAAG GCCAAGAGTG GGTCTTGACT AAATCCAT                        - (2) INFORMATION FOR SEQ ID NO:8:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 902 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:8:                                  #Leu Phe Ser Gly Phe Trprg Gln Ile Val Leu                                     #                 15                                                           #Val Gln Ile Gly Gly Leula Phe Pro Ser Ser                                     #             30                                                               #Ala Phe Arg Leu Ala Ilesp Gln Glu Tyr Thr                                     #         45                                                                   #Glu Ala Pro Phe Asn Leuer Pro Asn Ala Ser                                     #     60                                                                       #Asn Ser Phe Ala Val Thrsn Ile Glu Thr Ala                                     # 80                                                                           #Val Phe Ala Ile Phe Glyln Tyr Ser Arg Gly                                     #                 95                                                           #Thr Ser Phe Cys Arg Arger Val His Thr Leu                                     #            110                                                               #Pro Thr Glu Gly Glu Serle Thr Pro Ser Phe                                     #        125                                                                   #Arg Gly Ala Leu Leu Sereu Arg Pro Ser Leu                                     #    140                                                                       #Val Phe Leu Tyr Asp Thrlu Trp Asn Cys Phe                                     #160                                                                           #Met Glu Lys Ala Gly Glnle Leu Gln Ala Ile                                     #                175                                                           #Glu Asn Phe Asn Asp Valer Ala Ile Cys Val                                     #            190                                                               #Arg Arg Gln Glu Lys Lyseu Glu Glu Leu Asp                                     #        205                                                                   #Gln Asn Ile Leu Glu Glnlu Ile Glu Arg Leu                                     #    220                                                                       #Tyr His Tyr Ile Ile Alays His Val Lys Gly                                     #240                                                                           #Arg Phe Ile His Gly Glysp Ile Ser Leu Glu                                     #                255                                                           #Phe Asn Thr Pro Met Valhe Gln Leu Val Asp                                     #            270                                                               #Asp Gln Arg Glu Tyr Prorg Trp Lys Lys Leu                                     #        285                                                                   #Ala Leu Thr Tyr Asp Glyro Lys Tyr Thr Ser                                     #    300                                                                       #Leu Arg Arg Gln Lys Ilelu Thr Phe Arg Ser                                     #320                                                                           #Cys Leu Ala Asn Pro Alaly Asn Ala Gly Asp                                     #                335                                                           #Arg Thr Leu Lys Gln Vally Ile Asp Met Glu                                     #            350                                                               #Phe Asp His Tyr Gly Arghr Gly Asn Val Gln                                     #        365                                                                   #Leu Lys Ser Thr Gly Proet Asp Val Phe Glu                                     #    380                                                                       #Lys Leu Val Leu Ile Glnrp Asn Asp Met Asp                                     #400                                                                           #Ala Ile Glu Asn Arg Thrly Asn Asp Thr Ala                                     #                415                                                           #Tyr Val Met Tyr Lys Lysle Met Glu Ser Pro                                     #            430                                                               #Tyr Glu Gly Tyr Cys Vallu Gly Asn Asp Lys                                     #        445                                                                   #Gly Ile Lys Tyr Lys Ileer Ala Lys His Ile                                     #    460                                                                       #Arg Asp Ala Asp Thr Lysly Lys Tyr Gly Ala                                     #480                                                                           #Tyr Gly Lys Ala Glu Ileal Gly Glu Leu Val                                     #                495                                                           #Arg Glu Glu Val Ile Asphr Ile Thr Leu Val                                     #            510                                                               #Ser Ile Met Ile Lys Lyset Ser Leu Gly Ile                                     #        525                                                                   #Phe Leu Asp Pro Leu Alaro Gly Val Phe Ser                                     #    540                                                                       #Tyr Ile Gly Val Ser Valys Ile Val Phe Ala                                     #560                                                                           #Tyr Glu Trp His Thr Gluer Arg Phe Ser Pro                                     #                575                                                           #Asp Gln Pro Pro Asn Gluys Glu Gly Pro Ser                                     #            590                                                               #Leu Gly Ala Phe Met Glner Leu Trp Phe Ser                                     #        605                                                                   #Ser Gly Arg Ile Val Glyer Pro Arg Ser Leu                                     #    620                                                                       #Ile Ser Ser Tyr Thr Alahe Thr Leu Ile Ile                                     #640                                                                           #Met Val Ser Pro Ile Glueu Thr Val Glu Arg                                     #                655                                                           #Ile Ala Tyr Gly Thr Leula Lys Gln Thr Glu                                     #            670                                                               #Arg Ser Lys Ile Ala Valys Glu Phe Phe Arg                                     #        685                                                                   #Ala Glu Pro Ser Val Phehr Tyr Met Arg Ser                                     #    700                                                                       #Val Arg Lys Ser Lys Glylu Gly Val Ala Arg                                     #720                                                                           #Asn Glu Tyr Ile Glu Glneu Glu Ser Thr Met                                     #                735                                                           #Gly Asn Leu Asp Ser Lyshr Met Lys Val Gly                                     #            750                                                               #Ser Leu Arg Thr Pro Valhr Pro Lys Gly Ser                                     #        765                                                                   #Gly Val Leu Asp Lys Leuys Leu Ser Glu Ala                                     #    780                                                                       #Cys Gly Pro Lys Asp Seryr Asp Lys Gly Glu                                     #800                                                                           #Leu Ser Asn Val Ala Glyhr Ser Ala Leu Ser                                     #                815                                                           #Leu Ala Met Leu Val Alaal Gly Gly Leu Gly                                     #            830                                                               #Glu Ala Lys Arg Met Lysyr Lys Ser Arg Ala                                     #        845                                                                   #Ala Arg Leu Ser Ile Thrla Ile Arg Asn Lys                                     #    860                                                                       #Thr Pro Asp Cys Pro Lyssn Gly Arg Val Leu                                     #880                                                                           #Ser Ser Gly Leu Ala Valhr Ala Ile Arg Gln                                     #                895                                                           -  Ile Ala Ser Asp Leu Pro                                                                  900                                                               - (2) INFORMATION FOR SEQ ID NO:9:                                             -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 3250 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR5                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 188...2947                                                       (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:9:                                  #TCCTGAGAGC    60GCTTCAC GTCCCCACGC TTGTTCCCTC CACCTCGCTC                      #GACCCAGCCC   120TGTGCAG ACTCGGAGCA TTCCGGGAGG ATGAGGCGGG                      #ATTAAGAAGC   180CTTGCGG GCGTGAGGCC ACAACTGGGT TTCGGCATGA                      -  TTGAAAG ATG GAG CGC AGC ACA GTC CTT ATC C - #AA CCC GGG CTC TGG ACC          229                                                                                    Met Glu Arg Ser Thr V - #al Leu Ile Gln Pro Gly Leu Trp Thr           #       10                                                                     #CTG TGC TAC ATC CTC CCT     277TC TAT TTC                                     #Leu Cys Tyr Ile Leu Pro Leu Leu Tyr Phe                                       # 30                                                                           #GGG ATT TTT GAA ACT GTG     325GG ATC GGA                                     #Gly Ile Phe Glu Thr Val Leu Arg Ile Gly                                       #                 45                                                           #GCT TTC AAG TTT GCA GTC     373AA GAA TTA                                     #Ala Phe Lys Phe Ala Val Val Glu Glu Leu                                       #             60                                                               #CCC AAT ACC ACA TTA ACC     421CC TTG ATG                                     #Pro Asn Thr Thr Leu Thr Arg Thr Leu Met                                       #         75                                                                   #AGT TTT GAA GCC TCC CGA     469TT TTT GAT                                     #Ser Phe Glu Ala Ser Arg Asn Leu Phe Asp                                       #     90                                                                       #GCC GCA CTC TTC GGC CCT     517TC GGG GTG                                     #Ala Ala Leu Phe Gly Pro Ala Leu Gly Val                                       # 110                                                                          #TCT ATT TGC AAT GCT CTG     565CT GTA CAG                                     #Ser Ile Cys Asn Ala Leu Ser Ala Val Gln                                       #                125                                                           #CAC CCT TCC GTG GAC AGC     613GC TGG AAA                                     #His Pro Ser Val Asp Ser Thr Arg Trp Lys                                       #            140                                                               #GAC TAT GCG GCT ATC AGC     661TC TAC CCG                                     #Asp Tyr Ala Ala Ile Ser Asn Leu Tyr Pro                                       #        155                                                                   #AAC TGG AAA ACA GTG ACG     709TC TAT TAC                                     #Asn Trp Lys Thr Val Thr Val Leu Tyr Tyr                                       #    170                                                                       #CGT CTG CAA GAG CTC ATC     757GT CTA ATT                                     #Arg Leu Gln Glu Leu Ile Thr Gly Leu Ile                                       #190                                                                           #AAA ATC CGC CAG CTT CCC     805TT AAA ATC                                     #Lys Ile Arg Gln Leu Pro Asn Ile Lys Ile                                       #                205                                                           #AAG GAG ATG AAG AAA AGC     853CT CTG CTC                                     #Lys Glu Met Lys Lys Ser Lys Pro Leu Leu                                       #            220                                                               #CAC GAA ACA GCT GCG GAA     901AT TGT TCG                                     #His Glu Thr Ala Ala Glu Phe Asp Cys Ser                                       #        235                                                                   #ATG ACT GAA TAT TAT CAC     949TG GGC ATG                                     #Met Thr Glu Tyr Tyr His Phe Met Gly Met                                       #    250                                                                       #TTA GAT CTG GAA CTC TAT     997TG TTT GCT                                     #Leu Asp Leu Glu Leu Tyr Asp Leu Phe Ala                                       #270                                                                           #CGG TTG CTG AAT ATT GAC    1045CT GGA TTT                                     #Arg Leu Leu Asn Ile Asp Met Thr Gly Phe                                       #                285                                                           #TGG TCC ATG GAG AGG TTG    1093TT GAG AAG                                     #Trp Ser Met Glu Arg Leu Ile Ile Glu Lys                                       #            300                                                               #CTG GAT GGC ATG ATG ACA    1141CT GGT CTT                                     #Leu Asp Gly Met Met Thr Glu Thr Gly Leu                                       #        315                                                                   #TAC ATG GTA GCC ATT GCG    1189AT GCT GTG                                     #Tyr Met Val Ala Ile Ala Tyr Asp Ala Val                                       #    330                                                                       #TCC CTG CAG TGC CAT CGA    1237CC GTC AGC                                     #Ser Leu Gln Cys His Arg Leu Thr Val Ser                                       #350                                                                           #ATG AAC CTC ATC AAA GAG    1285CC AGA TTT                                     #Met Asn Leu Ile Lys Glu Gly Pro Arg Phe                                       #                365                                                           #ACC TTC AAT AAG ACC GAT    1333GG CGG ATC                                     #Thr Phe Asn Lys Thr Asp Thr Gly Arg Ile                                       #            380                                                               #ATC AGT CTC AAA GAG GAA    1381TG GAC ATT                                     #Ile Ser Leu Lys Glu Glu Asp Leu Asp Ile                                       #        395                                                                   #AAA CAC TTG TAT AAA GTG    1429AA GTG TCT                                     #Lys His Leu Tyr Lys Val Gly Glu Val Ser                                       #    410                                                                       #AGT GGG CTG AAC ATG ACG    1477AC TCC AAC                                     #Ser Gly Leu Asn Met Thr Trp Asn Ser Asn                                       #430                                                                           #ACG GAC TCG CTG GCT AAC    1525AC AAT ATC                                     #Thr Asp Ser Leu Ala Asn Ser Asn Asn Ile                                       #                445                                                           #GAG CCC TAC GTG ATG TAC    1573TT CTG GAA                                     #Glu Pro Tyr Val Met Tyr Thr Ile Leu Glu                                       #            460                                                               #GAC AGG TTT GAA GGA TAT    1621AT GGA AAC                                     #Asp Arg Phe Glu Gly Tyr Leu Tyr Gly Asn                                       #        475                                                                   #ATC CTG GGT TTT CTT TAC    1669TG TCC AAT                                     #Ile Leu Gly Phe Leu Tyr Glu Leu Ser Asn                                       #    490                                                                       #GGA GCA CAG AAT GAC AAA    1717GC AAA TAT                                     #Gly Ala Gln Asn Asp Lys Asp Gly Lys Tyr                                       #510                                                                           #ATC GAC CAC AGA GCT GAC    1765AA GAA CTC                                     #Ile Asp His Arg Ala Asp Val Lys Glu Leu                                       #                525                                                           #GTA CGG GAG AAA GTC ATT    1813TC ACA TAC                                     #Val Arg Glu Lys Val Ile Thr Ile Thr Tyr                                       #            540                                                               #ATT AGC ATC CTT TAC CGG    1861CC CTG GGC                                     #Ile Ser Ile Leu Tyr Arg Met Thr Leu Gly                                       #        555                                                                   #TCC TTC CTC AAC CCC CTA    1909GT GTC TTC                                     #Ser Phe Leu Asn Pro Leu Pro Gly Val Phe                                       #    570                                                                       #GCC TGC CTA GGA GTC AGT    1957TG CTG CTC                                     #Ala Cys Leu Gly Val Ser Tyr Val Leu Leu                                       #590                                                                           #CCC TAC GAG TGG TAT AAC    2005GG TTC ACA                                     #Pro Tyr Glu Trp Tyr Asn Ala Arg Phe Thr                                       #                605                                                           #GTG GAA AAC AAT TTC ACT    2053CA GAC GTG                                     #Val Glu Asn Asn Phe Thr Asp Ser Asp Val                                       #            620                                                               #GCT CTC ATG CAG CAA GGA    2101GA GTT GGA                                     #Ala Leu Met Gln Gln Gly Phe Gly Val Gly                                       #        635                                                                   #AGA ATA GTT GGA GGA ATA    2149TA TCG ACC                                     #Arg Ile Val Gly Gly Ile Ala Leu Ser Thr                                       #    650                                                                       #TCC TAC ACG GCC AAC CTG    2197TC ATT TCA                                     #Ser Tyr Thr Ala Asn Leu Ile Ile Ile Ser                                       #670                                                                           #TCC CCC ATC GAT TCC GCA    2245GA ATG GAA                                     #Ser Pro Ile Asp Ser Ala Glu Arg Met Glu                                       #                685                                                           #TAT GGG GCA GTC AGA GAT    2293AG ATA GAA                                     #Tyr Gly Ala Val Arg Asp Thr Lys Ile Glu                                       #            700                                                               #AAG ATC TCC ACC TAT GAG    2341AG AAA TCA                                     #Lys Ile Ser Thr Tyr Glu Phe Lys Lys Ser                                       #        715                                                                   #CAG AGC GCA CTG GTT AAA    2389GT AGA CAG                                     #Gln Ser Ala Leu Val Lys Ser Ser Arg Gln                                       #    730                                                                       #ACC ACC GAC TAC GCA CTG    2437GG GTG CTC                                     #Thr Thr Asp Tyr Ala Leu Gln Arg Val Leu                                       #750                                                                           #ACG CAG AGG AAC TGC AAC    2485AG TAT GTG                                     #Thr Gln Arg Asn Cys Asn Ile Glu Tyr Val                                       #                765                                                           #AAA GGC TAT GGA GTG GGG    2533TA GAC TCC                                     #Lys Gly Tyr Gly Val Gly Leu Ile Asp Ser                                       #            780                                                               #ATT ACG ATT GCC ATT CTT    2581GG GAT AAA                                     #Ile Thr Ile Ala Ile Leu Tyr Arg Asp Lys                                       #        795                                                                   #ATG AAA GAG AAG TGG TGG    2629TT CAT ATG                                     #Met Lys Glu Lys Trp Trp Lys Leu His Met                                       #    810                                                                       #AAG GAA GCC AGT GCT CTG    2677AA GAC AGT                                     #Lys Glu Ala Ser Ala Leu Glu Glu Asp Ser                                       #830                                                                           #GTT CTG GCT GCA GGA CTC    2725TC TTC ATT                                     #Val Leu Ala Ala Gly Leu Gly Ile Phe Ile                                       #                845                                                           #TTT TTA TAC AAA TCA CGG    2773TT GGA GAA                                     #Phe Leu Tyr Lys Ser Arg Ala Ile Gly Glu                                       #            860                                                               #TTC AAT GCC ATC ATG GAA    2821GT CTC TCT                                     #Phe Asn Ala Ile Met Glu Gln Cys Leu Ser                                       #        875                                                                   #AAA TTA AAG AAA AAG TCA    2869AT CAG AAA                                     #Lys Leu Lys Lys Lys Ser Lys Asn Gln Lys                                       #    890                                                                       #ATC CTT ACT TGT CAC CAG    2917TC ACA AGT                                     #Ile Leu Thr Cys His Gln Ser Phe Thr Ser                                       #910                                                                           #TGATCAAAGA ACACACCTGT AAG  2970CA GTG GCG                                      Arg Arg Thr Gln Arg Lys Glu Thr Val Ala                                       #                920                                                           #GGACTATGTC  3030CACGTCC GCTGCACATA TTTGGAGGAC AGATTTCAGA                      #TAAAGCTCAC  3090CCAGTCG TGGACAGAGG GGGAAGAAAT GCACAATTTT                      #GCACACTTAT  3150GAGAAGT GAAACTGATT CTTTTCAGAT GAATTTGTAT                      #AATAATAAAC  3210ATTTCCT CCGATAAATT GCTATGTGTG CTTTCTAAAT                      #  3250            TTCAT AAAAAAAAAA AAAAAAAAAA                                 - (2) INFORMATION FOR SEQ ID NO:10:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 920 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:10:                                 #Gly Leu Trp Thr Arg Aspal Leu Ile Gln Pro                                     #                 15                                                           #Tyr Ile Leu Pro Gln Threu Tyr Phe Leu Cys                                     #             30                                                               #Phe Glu Thr Val Glu Asnrg Ile Gly Gly Ile                                     #         45                                                                   #Lys Phe Ala Val Thr Serlu Glu Leu Ala Phe                                     #     60                                                                       #Thr Thr Leu Thr Tyr Asphr Leu Met Pro Asn                                     # 80                                                                           #Glu Ala Ser Arg Arg Alaeu Phe Asp Ser Phe                                     #                 95                                                           #Leu Phe Gly Pro Ser Hiseu Gly Val Ala Ala                                     #            110                                                               #Cys Asn Ala Leu Glu Valla Val Gln Ser Ile                                     #        125                                                                   #Ser Val Asp Ser Arg Asprg Trp Lys His Pro                                     #    140                                                                       #Ala Ala Ile Ser Arg Alaeu Tyr Pro Asp Tyr                                     #160                                                                           #Lys Thr Val Thr Val Valeu Tyr Tyr Asn Trp                                     #                175                                                           #Gln Glu Leu Ile Lys Alaly Leu Ile Arg Leu                                     #            190                                                               #Arg Gln Leu Pro Pro Alale Lys Ile Lys Ile                                     #        205                                                                   #Met Lys Lys Ser Lys Gluro Leu Leu Lys Glu                                     #    220                                                                       #Thr Ala Ala Glu Ile Leusp Cys Ser His Glu                                     #240                                                                           #Glu Tyr Tyr His Tyr Pheet Gly Met Met Thr                                     #                255                                                           #Leu Glu Leu Tyr Arg Tyreu Phe Ala Leu Asp                                     #            270                                                               #Leu Asn Ile Asp Asn Prohr Gly Phe Arg Leu                                     #        285                                                                   #Met Glu Arg Leu Gln Alale Glu Lys Trp Ser                                     #    300                                                                       #Gly Met Met Thr Thr Gluhr Gly Leu Leu Asp                                     #320                                                                           #Val Ala Ile Ala Ser Hissp Ala Val Tyr Met                                     #                335                                                           #Gln Cys His Arg His Lyshr Val Ser Ser Leu                                     #            350                                                               #Leu Ile Lys Glu Ala Argro Arg Phe Met Asn                                     #        365                                                                   #Asn Lys Thr Asp Gly Leuly Arg Ile Thr Phe                                     #    380                                                                       #Leu Lys Glu Glu Gly Threu Asp Ile Ile Ser                                     #400                                                                           #Leu Tyr Lys Val Trp Lyslu Val Ser Lys His                                     #                415                                                           #Leu Asn Met Thr Asp Glysn Ser Asn Ser Gly                                     #            430                                                               #Ser Leu Ala Asn Arg Thrsn Asn Ile Thr Asp                                     #        445                                                                   #Tyr Val Met Tyr Arg Lysle Leu Glu Glu Pro                                     #    460                                                                       #Phe Glu Gly Tyr Cys Leuyr Gly Asn Asp Arg                                     #480                                                                           #Gly Phe Leu Tyr Asp Valeu Ser Asn Ile Leu                                     #                495                                                           #Gln Asn Asp Lys Gly Gluly Lys Tyr Gly Ala                                     #            510                                                               #His Arg Ala Asp Leu Alays Glu Leu Ile Asp                                     #        525                                                                   #Glu Lys Val Ile Asp Phele Thr Tyr Val Arg                                     #    540                                                                       #Ile Leu Tyr Arg Lys Prohr Leu Gly Ile Ser                                     #560                                                                           #Leu Asn Pro Leu Ser Proly Val Phe Ser Phe                                     #                575                                                           #Leu Gly Val Ser Cys Valal Leu Leu Ala Cys                                     #            590                                                               #Glu Trp Tyr Asn Pro Hisrg Phe Thr Pro Tyr                                     #        605                                                                   #Asn Asn Phe Thr Leu Leuer Asp Val Val Glu                                     #    620                                                                       #Met Gln Gln Gly Ser Gluly Val Gly Ala Leu                                     #640                                                                           #Val Gly Gly Ile Trp Trpeu Ser Thr Arg Ile                                     #                655                                                           #Thr Ala Asn Leu Ala Alale Ile Ser Ser Tyr                                     #            670                                                               #Ile Asp Ser Ala Asp Asprg Met Glu Ser Pro                                     #        685                                                                   #Ala Val Arg Asp Gly Serys Ile Glu Tyr Gly                                     #    700                                                                       #Ser Thr Tyr Glu Lys Metys Lys Ser Lys Ile                                     #720                                                                           #Ala Leu Val Lys Asn Serer Arg Gln Gln Ser                                     #                735                                                           #Asp Tyr Ala Leu Leu Metrg Val Leu Thr Thr                                     #            750                                                               #Arg Asn Cys Asn Leu Thrlu Tyr Val Thr Gln                                     #        765                                                                   #Tyr Gly Val Gly Thr Prole Asp Ser Lys Gly                                     #    780                                                                       #Ile Ala Ile Leu Gln Leurg Asp Lys Ile Thr                                     #800                                                                           #Glu Lys Trp Trp Arg Glyeu His Met Met Lys                                     #                815                                                           #Ala Ser Ala Leu Gly Vallu Asp Ser Lys Glu                                     #            830                                                               #Ala Ala Gly Leu Val Leule Phe Ile Val Leu                                     #        845                                                                   #Tyr Lys Ser Arg Lys Asnle Gly Glu Phe Leu                                     #    860                                                                       #Ala Ile Met Glu Glu Leuys Leu Ser Phe Asn                                     #880                                                                           #Lys Lys Lys Ser Arg Thrsn Gln Lys Lys Leu                                     #                895                                                           #Thr Cys His Gln Arg Arghe Thr Ser Ile Leu                                     #            910                                                               -  Thr Gln Arg Lys Glu Thr Val Ala                                             #        920                                                                   - (2) INFORMATION FOR SEQ ID NO:11:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 4608 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR6                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 307...2958                                                       (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:11:                                 #TTTTCCCGGA    60CAAGGGC TTCGCAGGCT GGACATTGTG CTTGCTGGAT                      #CTCCTTGGCG   120ACATGGA TGTCCCACCA TCCCTTGCAG TGGAAGCTTG                      #GACTCCTTCC   180GAACATG CAGCGACTGC TAATGGGTTT GGGAAGCGGA                      #CTTCCTTCTC   240ATGCCGT GATTGTGTCT GCGGCCACTA CTCCACGCAT                      #CAGGCACGGA   300GCCTAAC GCTAGATCGG GGAAGTGGGT GCCGCGCGCG                      -  AACATC ATG AAG ATT ATT TCC CCA GTT TTA AG - #T AAT CTA GTC TTC AGT           348                                                                           #Val Leu Ser Asn Leu Val Phe Ser                                               #      10                                                                      #TGG ATC GGA TAT TCG CAA     396GC TTA TTG                                     #Trp Ile Gly Tyr Ser Gln Leu Cys Leu Leu                                       # 30                                                                           #ATA TTT GAA TAT GTG GAA     444TC GGT GGT                                     #Ile Phe Glu Tyr Val Glu Arg Phe Gly Gly                                       #                 45                                                           #TTC AGA TTT GCT GTG AAT     492AA CTT GCA                                     #Phe Arg Phe Ala Val Asn Glu Glu Leu Ala                                       #             60                                                               #AAC ACC ACT TTA ACT TAT     540TG CTG CCC                                     #Asn Thr Thr Leu Thr Tyr Thr Leu Leu Pro                                       #         75                                                                   #TTT GAA GCA TCT AAG AAA     588AT GAC AGT                                     #Phe Glu Ala Ser Lys Lys Leu Tyr Asp Ser                                       #     90                                                                       #GCT ATC TTC GGT CCT TCA     636GG GTG GCT                                     #Ala Ile Phe Gly Pro Ser Leu Gly Val Ala                                       # 110                                                                          #ATC TGC AAT GCT CTG GGG     684TG CAG TCC                                     #Ile Cys Asn Ala Leu Gly Ala Val Gln Ser                                       #                125                                                           #CAG GTG TCA GAC AAC AAG     732GG AAG CAC                                     #Gln Val Ser Asp Asn Lys Arg Trp Lys His                                       #            140                                                               #TTC TCT TCC CTG AGC CGC     780AC CCA GAC                                     #Phe Ser Ser Leu Ser Arg Leu Tyr Pro Asp                                       #        155                                                                   #TGG AAA ACT GTC ACA GTT     828TT TTT AAG                                     #Trp Lys Thr Val Thr Val Gln Phe Phe Lys                                       #    170                                                                       #TTG CAA GAG CTC ATC AAA     876TC ATT CGC                                     #Leu Gln Glu Leu Ile Lys Gly Leu Ile Arg                                       #190                                                                           #ATT CGT CAG CTG CCA GCT     924GA CTT AAA                                     #Ile Arg Gln Leu Pro Ala Leu Arg Leu Lys                                       #                205                                                           #GAG ATG AAA AGA GGC AAG     972TG CTG AAG                                     #Glu Met Lys Arg Gly Lys Pro Leu Leu Lys                                       #            220                                                               #GAG ATG GCA GCA GGC ATT    1020GC AGC CAT                                     #Glu Met Ala Ala Gly Ile Asp Cys Ser His                                       #        235                                                                   #ACA GAA TAC TAT CAC TAT    1068GA ATG ATG                                     #Thr Glu Tyr Tyr His Tyr Met Gly Met Met                                       #    250                                                                       #GAC GTG GAG CCC TAC AGA    1116TT GCT CTT                                     #Asp Val Glu Pro Tyr Arg Leu Phe Ala Leu                                       #270                                                                           #ATA CTA AAT ACA GAG AAT    1164GG TTC AGG                                     #Ile Leu Asn Thr Glu Asn Thr Gly Phe Arg                                       #                285                                                           #TCT ATG GAA CGG TTA CAG    1212AA AAG TGG                                     #Ser Met Glu Arg Leu Gln Ile Glu Lys Trp                                       #            300                                                               #GAT GGA TTT ATG ACG ACT    1260GT TTG CTG                                     #Asp Gly Phe Met Thr Thr Ser Gly Leu Leu                                       #        315                                                                   #GTT GTG TCT GTG GCT GTC    1308CA GTG CAC                                     #Val Val Ser Val Ala Val Asp Ala Val His                                       #    330                                                                       #TTG CAA TGC AAT CGA CAC    1356TC AGC TCC                                     #Leu Gln Cys Asn Arg His Thr Val Ser Ser                                       #350                                                                           #AGT CTA ATT AAA GAG GCT    1404GC TTC ATG                                     #Ser Leu Ile Lys Glu Ala Thr Arg Phe Met                                       #                365                                                           #TTT AAC AAA ACC AAT GGA    1452GA ATA ACA                                     #Phe Asn Lys Thr Asn Gly Gly Arg Ile Thr                                       #            380                                                               #AGT CTC AAG GAA GAA GGT    1500AT GTG ATC                                     #Ser Leu Lys Glu Glu Gly Leu Asp Val Ile                                       #        395                                                                   #AGT GGC CTG AAT ATG ACA    1548AT CCA GCC                                     #Ser Gly Leu Asn Met Thr Trp Asp Pro Ala                                       #    410                                                                       #ACA GAC TCA TTG TCT AAT    1596CA AAT ATC                                     #Thr Asp Ser Leu Ser Asn Pro Ala Asn Ile                                       #430                                                                           #GAA CCG TAT GTT CTG TTT    1644TT TTG GAA                                     #Glu Pro Tyr Val Leu Phe Thr Ile Leu Glu                                       #                445                                                           #GAT CGA TTT GAA GGC TAC    1692AT GGG AAT                                     #Asp Arg Phe Glu Gly Tyr Leu Tyr Gly Asn                                       #            460                                                               #ATC CTT GGC TTT ACA TAT    1740TA TCT ACA                                     #Ile Leu Gly Phe Thr Tyr Glu Leu Ser Thr                                       #        475                                                                   #GGA GCC CAG GAT GAT GTG    1788GG AAA TAT                                     #Gly Ala Gln Asp Asp Val Asp Gly Lys Tyr                                       #    490                                                                       #CTA ATC GAT CAT AAA GCT    1836TT CGT GAA                                     #Leu Ile Asp His Lys Ala Met Val Arg Glu                                       #510                                                                           #TAT GTT CGT GAG AAG GTC    1884CT ATA ACC                                     #Tyr Val Arg Glu Lys Val Leu Ala Ile Thr                                       #                525                                                           #GGA ATA AGT ATT TTG TAC    1932TG ACA CTT                                     #Gly Ile Ser Ile Leu Tyr Phe Met Thr Leu                                       #            540                                                               #TTC TCC TTC CTG AAT CCT    1980CA GGC GTC                                     #Phe Ser Phe Leu Asn Pro Asn Pro Gly Val                                       #        555                                                                   #CTG GCT TGC TTG GGT GTC    2028AT GTT CTG                                     #Leu Ala Cys Leu Gly Val Met Tyr Val Leu                                       #    570                                                                       #AGT CCC TAT GAG TGG TAT    2076CC AGG TTT                                     #Ser Pro Tyr Glu Trp Tyr Ile Ala Arg Phe                                       #590                                                                           #GTG GTG GAA AAC AAT TTT    2124AC TCA GAC                                     #Val Val Glu Asn Asn Phe Pro Asp Ser Asp                                       #                605                                                           #GGA GCT CTC ATG CGG CAA    2172TT GGA GTT                                     #Gly Ala Leu Met Arg Gln Trp Phe Gly Val                                       #            620                                                               #ACC AGG ATA GTG GGA GGC    2220CA CTC TCC                                     #Thr Arg Ile Val Gly Gly Lys Ala Leu Ser                                       #        635                                                                   #TCT TCG TAT ACC GCT AAC    2268TC ATC ATT                                     #Ser Ser Tyr Thr Ala Asn Leu Ile Ile Ile                                       #    650                                                                       #GAG TCG CCC ATT GAC TCT    2316AA CGC ATG                                     #Glu Ser Pro Ile Asp Ser Val Glu Arg Met                                       #670                                                                           #GAG TAT GGA GCA GTG GAG    2364CC AAG ATA                                     #Glu Tyr Gly Ala Val Glu Gln Thr Lys Ile                                       #                685                                                           #TCA AAA ATT TCA ACG TAT    2412TT AAG AAA                                     #Ser Lys Ile Ser Thr Tyr Phe Phe Lys Lys                                       #            700                                                               #AGA CAG TCT GTG CTT GTC    2460GC AGC AGG                                     #Arg Gln Ser Val Leu Val Met Ser Ser Arg                                       #        715                                                                   #CTC ACC TCG GAT TAT GCT    2508AA CGA GTC                                     #Leu Thr Ser Asp Tyr Ala Ile Gln Arg Val                                       #    730                                                                       #GTT ACA CAG CGG AAC TGT    2556TC GAG TTT                                     #Val Thr Gln Arg Asn Cys Thr Ile Glu Phe                                       #750                                                                           #TCC AAA GGC TAT GGC GTT    2604TT ATA GAC                                     #Ser Lys Gly Tyr Gly Val Gly Leu Ile Asp                                       #                765                                                           #AAA ATC ACC ATA GCA ATT    2652AT CGA GAC                                     #Lys Ile Thr Ile Ala Ile Pro Tyr Arg Asp                                       #            780                                                               #ATG ATG AAG GAG AAA TGG    2700AG CTG CAC                                     #Met Met Lys Glu Lys Trp Gly Lys Leu His                                       #        795                                                                   #AGC AAA GAG GCC AGT GCT    2748AG GAG GAG                                     #Ser Lys Glu Ala Ser Ala Pro Glu Glu Glu                                       #    810                                                                       #ATT GTC CTG GCA GCC GGC    2796GT ATC TTC                                     #Ile Val Leu Ala Ala Gly Gly Gly Ile Phe                                       #830                                                                           #GAG TTT TTA TAC AAA TCC    2844CA GTG GGA                                     #Glu Phe Leu Tyr Lys Ser Val Ala Val Gly                                       #                845                                                           #TTC TGT AGC GCT ATG GTG    2892AG AGG TCC                                     #Phe Cys Ser Ala Met Val Glu Lys Arg Ser                                       #            860                                                               #CGT CGG CTC AAA CAT AAG    2940AG TGC CAG                                     #Arg Arg Leu Lys His Lys Leu Lys Cys Gln                                       #        875                                                                   #AACATGCACA CATTTAAC  2996 TGAAAACAGA AGAAGTTATC                                Pro Gln Pro Gln Leu Leu                                                            880                                                                       #TCACCCAAGC  3056CAGGTAA AGAAACCATG GCATGAAGCT GGGAGGCCAA                      #TTTCCTGTGG  3116TTTTTTT TTTTTTTTTC CAAACAATTT AGCGAGAATG                      #TATGAACTAG  3176GTGCAAA ATAAAATGAG TTACCTCATG CCGCTGTGTC                      #CGTGGATCAA  3236TAAGCAG TTTCAGTGAT CAGACTTGAT TTACAAGCAC                      #AGTGAATGTT  3296GGTTACA CTGTTTATCA TAGGTTCCTC CCTTCCTTTG                      #GGTTCCTTCT  3356GTGGCTG GTTTCAAATG CAGTCCAGGG AGAAACTGCT                      #CAATAAAAAT  3416CGTCAGG AGATGGAATG CCGGTGCCCA AAAGGGTAAC                      #ACAAGAAACA  3476TAAAAAA ATGCGTGAGA TCGGCAAAAA TTATAGTGTT                      #CCAATACTCA  3536GTCACCA ACACAATAGA GGTGATAATG TTACTAGCCC                      #AATGTAATGC  3596CTGAATA GATAATATGT GTTCATAGAA TGTGAAAAAA                      #TTACTTTTCT  3656ATCAATA GAAGTGGAAC TGAAGGCAGA ACATCATCAG                      #CAATAATTTT  3716GTGTCAT GGATTGTGAT ATAGATGGCA ATTATCAAGC                      #AAATCCCTAC  3776CCTATGG CAAATATTTT AATAGGCAAC TTGCTCCCAC                      #TGTAAGAGAT  3836AGAAATA TAAAAGGAAC CATTGGTTTA GAGATTGGTA                      #TTACAGGGAA  3896CCTTGTC GTGCATTGTA AAAGGGCTCA GTGTTACTGG                      #CCTCCTGTAA  3956ACCCTGA CATTCTGAAA TGTCAACCGA AACTCTCCTT                      #CTATACAATG  4016GGCAGAT TCCATTGATC AAAGAATGGG GACTTGTCAC                      #TAAAAGAACA  4076CTTTGAG GTGGACTGCA TTTAATAATA GTCACAATGT                      #TTCAGGTTTA  4136GTTTTTT TTTTTTGTTT TGTTTTGTTT TCAAAAAATG                      #GTAATACTTT  4196AAGATTT CTATAAAATA GTTTTTGTAT GGAAATTTTT                      #ATGAACGGTA  4256AAGAACA CATGTTTCTG TCAGGGGTGT GAGGTCAAGC                      #GAATCATAGA  4316ACCAACG TTTGGTGAAA CTATTTTTAT CAAGAAAAAG                      #ACGGCTTGTC  4376CAAGTTA GATACTATAA AAGCTAGGTG CACTACCACC                      #TGTGTGTAAA  4436GAGTCCA CAAGGTGGAT AACATATTGT AATGAACAGT                      #ACACAGTTTG  4496CAGACCT CTTGACAACA TTGTGAAAAC AGTTGAGTGC                      #TCCGTTTTAA  4556ATGCACA AAAATTTTAC AAAAATCCAT TAAAATTATG                      #CC          4608GGGGATC CACTAGTTCT AGAGCCGGTG CCCAATTCGC                      - (2) INFORMATION FOR SEQ ID NO:12:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 884 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:12:                                 #Leu Val Phe Ser Arg Serro Val Leu Ser Asn                                     #                 15                                                           #Gly Tyr Ser Gln Gly Thrys Leu Leu Trp Ile                                     #             30                                                               #Glu Tyr Val Glu Ser Glyhe Gly Gly Ile Phe                                     #         45                                                                   #Phe Ala Val Asn Thr Ilelu Leu Ala Phe Arg                                     #     60                                                                       #Thr Leu Thr Tyr Asp Threu Leu Pro Asn Thr                                     # 80                                                                           #Ala Ser Lys Lys Ala Cysyr Asp Ser Phe Glu                                     #                 95                                                           #Phe Gly Pro Ser His Serly Val Ala Ala Ile                                     #            110                                                               #Asn Ala Leu Gly Val Proal Gln Ser Ile Cys                                     #        125                                                                   #Ser Asp Asn Lys Asp Serrp Lys His Gln Val                                     #    140                                                                       #Ser Leu Ser Arg Ala Ileyr Pro Asp Phe Ser                                     #160                                                                           #Thr Val Thr Val Val Tyrhe Phe Lys Trp Lys                                     #                175                                                           #Glu Leu Ile Lys Ala Proeu Ile Arg Leu Gln                                     #            190                                                               #Gln Leu Pro Ala Asp Thrrg Leu Lys Ile Arg                                     #        205                                                                   #Lys Arg Gly Lys Glu Pheeu Leu Lys Glu Met                                     #    220                                                                       #Ala Ala Gly Ile Leu Lysys Ser His Glu Met                                     #240                                                                           #Tyr Tyr His Tyr Ile Phely Met Met Thr Glu                                     #                255                                                           #Glu Pro Tyr Arg Tyr Serhe Ala Leu Asp Val                                     #            270                                                               #Asn Thr Glu Asn Thr Glnly Phe Arg Ile Leu                                     #        285                                                                   #Glu Arg Leu Gln Ala Prolu Lys Trp Ser Met                                     #    300                                                                       #Phe Met Thr Thr Asp Alaly Leu Leu Asp Gly                                     #320                                                                           #Ser Val Ala Val Gln Glnla Val His Val Val                                     #                335                                                           #Cys Asn Arg His Lys Proal Ser Ser Leu Gln                                     #            350                                                               #Ile Lys Glu Ala His Trprg Phe Met Ser Leu                                     #        365                                                                   #Lys Thr Asn Gly Leu Argrg Ile Thr Phe Asn                                     #    380                                                                       #Lys Glu Glu Gly Leu Glusp Val Ile Ser Leu                                     #400                                                                           #Leu Asn Met Thr Glu Sersp Pro Ala Ser Gly                                     #                415                                                           #Ser Leu Ser Asn Arg Serla Asn Ile Thr Asp                                     #            430                                                               #Tyr Val Leu Phe Lys Lysle Leu Glu Glu Pro                                     #        445                                                                   #Phe Glu Gly Tyr Cys Ileyr Gly Asn Asp Arg                                     #    460                                                                       #Gly Phe Thr Tyr Glu Ileeu Ser Thr Ile Leu                                     #480                                                                           #Gln Asp Asp Val Asn Glyly Lys Tyr Gly Ala                                     #                495                                                           #Asp His Lys Ala Asp Leual Arg Glu Leu Ile                                     #            510                                                               #Arg Glu Lys Val Ile Aspla Ile Thr Tyr Val                                     #        525                                                                   #Ser Ile Leu Tyr Arg Lyset Thr Leu Gly Ile                                     #    540                                                                       #Phe Leu Asn Pro Leu Serro Gly Val Phe Ser                                     #560                                                                           #Cys Leu Gly Val Ser Cysyr Val Leu Leu Ala                                     #                575                                                           #Tyr Glu Trp Tyr Asn Prola Arg Phe Ser Pro                                     #            590                                                               #Glu Asn Asn Phe Thr Leusp Ser Asp Val Val                                     #        605                                                                   #Leu Met Arg Gln Gly Serhe Gly Val Gly Ala                                     #    620                                                                       #Ile Val Gly Gly Ile Trpla Leu Ser Thr Arg                                     #640                                                                           #Tyr Thr Ala Asn Leu Alale Ile Ile Ser Ser                                     #                655                                                           #Pro Ile Asp Ser Ala Asplu Arg Met Glu Ser                                     #            670                                                               #Gly Ala Val Glu Asp Glyhr Lys Ile Glu Tyr                                     #        685                                                                   #Ile Ser Thr Tyr Asp Lyshe Lys Lys Ser Lys                                     #    700                                                                       #Ser Val Leu Val Lys Serer Ser Arg Arg Gln                                     #720                                                                           #Ser Asp Tyr Ala Phe Leuln Arg Val Leu Thr                                     #                735                                                           #Gln Arg Asn Cys Asn Leule Glu Phe Val Thr                                     #            750                                                               #Gly Tyr Gly Val Gly Threu Ile Asp Ser Lys                                     #        765                                                                   #Thr Ile Ala Ile Leu Glnyr Arg Asp Lys Ile                                     #    780                                                                       #Lys Glu Lys Trp Trp Argys Leu His Met Met                                     #800                                                                           #Glu Ala Ser Ala Leu Glylu Glu Glu Ser Lys                                     #                815                                                           #Leu Ala Ala Gly Leu Vally Ile Phe Ile Val                                     #            830                                                               #Leu Tyr Lys Ser Lys Lysla Val Gly Glu Phe                                     #        845                                                                   #Ser Ala Met Val Glu Gluys Arg Ser Phe Cys                                     #    860                                                                       #Leu Lys His Lys Pro Glnys Cys Gln Arg Arg                                     #880                                                                           -  Pro Gln Leu Leu                                                             - (2) INFORMATION FOR SEQ ID NO:13:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #pairs    (A) LENGTH: 3344 base                                                          (B) TYPE: nucleic acid                                                         (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: cDNA                                                 -    (vii) IMMEDIATE SOURCE:                                                             (B) CLONE: GluR7                                                     -     (ix) FEATURE:                                                                      (A) NAME/KEY: Coding Se - #quence                                              (B) LOCATION: 1...2763                                                         (D) OTHER INFORMATION:                                               -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:13:                                 #CGG AGT CTG GTT TGG GAA      48GG CGC CTC                                     #Arg Ser Leu Val Trp Glu Leu Gly Arg Leu                                       #                 15                                                           #TGG ATC CCA GAC TCG CGC      96GC GCC TTC                                     #Trp Ile Pro Asp Ser Arg Val Cys Ala Phe                                       #             30                                                               #ATC TTT GAG TAC GCG GAC     144TC GGC GGA                                     #Ile Phe Glu Tyr Ala Asp Arg Ile Gly Gly                                       #         45                                                                   #GAG CAC GCC TTT CGG TTT     192AC GCT GAG                                     #Glu His Ala Phe Arg Phe Met Asn Ala Glu                                       #     60                                                                       #CTG CTG CCC AAC ACG ACC     240AC AGA ACT                                     #Leu Leu Pro Asn Thr Thr Arg Asn Arg Thr                                       # 80                                                                           #CAT GAC AGT TTT GAG GCC     288TT CAC TTC                                     #His Asp Ser Phe Glu Ala Arg Ile His Phe                                       #                 95                                                           #GGT GTG GTA GCC ATC TTT     336TG GCG CTC                                     #Gly Val Val Ala Ile Phe Gln Leu Ala Leu                                       #            110                                                               #GTC CAG TCC ATC TGC AAT     384TC AAT GCC                                     #Val Gln Ser Ile Cys Asn Cys Ile Asn Ala                                       #        125                                                                   #TGG AAG CAC CAC CCC CTG     432AA CTG CGC                                     #Trp Lys His His Pro Leu Ile Gln Leu Arg                                       #    140                                                                       #TAC CCC GAC TAC GCC TCT     480TG AAC CTC                                     #Tyr Pro Asp Tyr Ala Ser Tyr Val Asn Leu                                       #160                                                                           #TCC CTC AAG TGG CGG TCA     528TG GTC CAG                                     #Ser Leu Lys Trp Arg Ser Asp Leu Val Gln                                       #                175                                                           #CTC ATC CGG CTG CAG GAG     576GT ACA GGT                                     #Leu Ile Arg Leu Gln Glu Asp Ser Thr Gly                                       #            190                                                               #CGC CTG AAG ATT CGC CAG     624AC AAC ATC                                     #Arg Leu Lys Ile Arg Gln Arg Tyr Asn Ile                                       #        205                                                                   #TTG CTC AAA GAG ATG AAG     672CA CGC CCC                                     #Leu Leu Lys Glu Met Lys Asp Ser Arg Pro                                       #    220                                                                       #TGC AGT CAC ACC ATG GCA     720TC TTT GAC                                     #Cys Ser His Thr Met Ala Ile Ile Phe Asp                                       #240                                                                           #GGC ATG ATG ACG GAA TAC     768TG GCC ATG                                     #Gly Met Met Thr Glu Tyr Ala Met Ala Met                                       #                255                                                           #TAT GCG CTA GAC CTG GAA     816TG GAT CTC                                     #Tyr Ala Leu Asp Leu Glu Thr Leu Asp Leu                                       #            270                                                               #GGG TTC CGC ATA CTC AAC     864AC CTG ACT                                     #Gly Phe Arg Ile Leu Asn Val Asn Leu Thr                                       #        285                                                                   #GAG AAG TGG TCC ATG GAG     912CC ATT GTG                                     #Glu Lys Trp Ser Met Glu Ser Ala Ile Val                                       #    300                                                                       #GGC CTG CTG GAT GGA GTG     960CA GAG TCA                                     #Gly Leu Leu Asp Gly Val Arg Ala Glu Ser                                       #320                                                                           #GCG GTC CAC ATT GTG TCT    1008TC TAC GAT                                     #Ala Val His Ile Val Ser Leu Leu Tyr Asp                                       #                335                                                           #GTG AAC TCC CTA CAG TGC    1056AG ATG ACT                                     #Val Asn Ser Leu Gln Cys Pro Gln Met Thr                                       #            350                                                               #CGC TTC ATG AAC TTC ATC    1104TC GGT GGC                                     #Arg Phe Met Asn Phe Ile Arg Phe Gly Gly                                       #        365                                                                   #CGG ATT GTT TTC AAC AAA    1152TA ACT GGA                                     #Arg Ile Val Phe Asn Lys Gly Leu Thr Gly                                       #    380                                                                       #GAC ATC ATC AGC CTC AAG    1200TT GAT CTG                                     #Asp Ile Ile Ser Leu Lys Asp Phe Asp Leu                                       #400                                                                           #AGT CCA GCT GAC GGT CTC    1248GG GTG TGG                                     #Ser Pro Ala Asp Gly Leu Val Gly Val Trp                                       #                415                                                           #CCT AAT GTC ACC GAC TCT    1296GC CGA GGT                                     #Pro Asn Val Thr Asp Ser Lys Gly Arg Gly                                       #            430                                                               #CTG CTG GAG GAG CCT TTT    1344TC ACC ACT                                     #Leu Leu Glu Glu Pro Phe Ile Val Thr Thr                                       #        445                                                                   #TAC GGC AAT GAC CGG TTC    1392GG ACC CTT                                     #Tyr Gly Asn Asp Arg Phe Asp Arg Thr Leu                                       #    460                                                                       #CTG GCG CAC ATC CTG GGC    1440TC AAG GAG                                     #Leu Ala His Ile Leu Gly Leu Leu Lys Glu                                       #480                                                                           #GGC AAG TAC GGG GCA CAG    1488TG GAA GAC                                     #Gly Lys Tyr Gly Ala Gln Leu Val Glu Asp                                       #                495                                                           #AAG GAA CTC ATT GAC CAC    1536GC ATG GTC                                     #Lys Glu Leu Ile Asp His Asn Gly Met Val                                       #            510                                                               #ATC ACC CAT GTC CGA GAG    1584CC CTG ACC                                     #Ile Thr His Val Arg Glu Ala Pro Leu Thr                                       #        525                                                                   #ACC CTC GGA GTG AGC ATC    1632CT TTT ATG                                     #Thr Leu Gly Val Ser Ile Lys Pro Phe Met                                       #    540                                                                       #AGT GTC TTC TCC TTC CTC    1680CC AAC CCC                                     #Ser Val Phe Ser Phe Leu Gly Thr Asn Pro                                       #560                                                                           #GTG CTA CTC GCC TAC CTG    1728GG ATG TAC                                     #Val Leu Leu Ala Tyr Leu Ile Trp Met Tyr                                       #                575                                                           #AGA TTC AGC CCT TAT GAA    1776TC ATT GCC                                     #Arg Phe Ser Pro Tyr Glu Phe Val Ile Ala                                       #            590                                                               #TCT GAG GTG GTG GAG AAT    1824AC CCC GGC                                     #Ser Glu Val Val Glu Asn Cys Asn Pro Gly                                       #        605                                                                   #GGA ATG GGC TCC CTG ATG    1872TC TGG TTT                                     #Gly Met Gly Ser Leu Met Ser Phe Trp Phe                                       #    620                                                                       #CTG TCT ACC CGC ATC ATT    1920CC AAA GCT                                     #Leu Ser Thr Arg Ile Ile Met Pro Lys Ala                                       #640                                                                           #ATC ATC TCC TCC TAC ACG    1968CC CTT ATT                                     #Ile Ile Ser Ser Tyr Thr Phe Thr Leu Ile                                       #                655                                                           #CGC ATG GAG TCA CCC ATC    2016CC GTG GAG                                     #Arg Met Glu Ser Pro Ile Leu Thr Val Glu                                       #            670                                                               #AAA ATA GAG TAC GGT GCT    2064AG CAG ACC                                     #Lys Ile Glu Tyr Gly Ala Ala Lys Gln Thr                                       #        685                                                                   #AAG AAA TCC AAG ATC TCC    2112CC TTC TTC                                     #Lys Lys Ser Lys Ile Ser Met Thr Phe Phe                                       #    700                                                                       #AGC AAG CCC TCG GCT CTG    2160TC ATG AGC                                     #Ser Lys Pro Ser Ala Leu Ala Phe Met Ser                                       #720                                                                           #ACA CTC ACA GCT GAC TAC    2208TC CAG CGG                                     #Thr Leu Thr Ala Asp Tyr Gly Ile Gln Arg                                       #                735                                                           #TAC ATC ACA CAA AGG AAC    2256CC ATA GAG                                     #Tyr Ile Thr Gln Arg Asn Thr Thr Ile Glu                                       #            750                                                               #GAT TCC AAG GGC TAC GGC    2304GC CTC ATC                                     #Asp Ser Lys Gly Tyr Gly Gly Gly Leu Ile                                       #        765                                                                   #GAC AAA ATC ACC ATC GCC    2352CC TAC AGG                                     #Asp Lys Ile Thr Ile Ala Ser Pro Tyr Arg                                       #    780                                                                       #CAC ATC ATG AAG GAG AAG    2400AC AAG CTG                                     #His Ile Met Lys Glu Lys Glu Asp Lys Leu                                       #800                                                                           #GAG AAC AAG GAG GCC AGC    2448CC GAG GAG                                     #Glu Asn Lys Glu Ala Ser Cys Pro Glu Glu                                       #                815                                                           #TTC ATC GTC CTG GCT GCC    2496GC GGC ATC                                     #Phe Ile Val Leu Ala Ala Ile Gly Gly Ile                                       #            830                                                               #GGC GAG TTT ATA TAC AAA    2544TG GCA GTG                                     #Gly Glu Phe Ile Tyr Lys Leu Val Ala Val                                       #        845                                                                   #TCT TTC TGC AGC ACA GTG    2592AG CAG CGC                                     #Ser Phe Cys Ser Thr Val Arg Glu Gln Arg                                       #    860                                                                       #CAG CGG CGT CTC AAG CAC    2640TC ACC TGC                                     #Gln Arg Arg Leu Lys His Ser Leu Thr Cys                                       #880                                                                           #GAT GCG GTT ATC AAC ATG    2688TC AAG ACA                                     #Asp Ala Val Ile Asn Met Met Val Lys Thr                                       #                895                                                           #AAG GAC AGC ATG AGC TGC    2736TT CCA GGC                                     #Lys Asp Ser Met Ser Cys Arg Leu Pro Gly                                       #            910                                                               -  AGC ACC TCG CTA GCC CCT GTC TTC CCT TAGAC - #TTGGG TCCAGCGGGG ACTTCAG       2790                                                                            Ser Thr Ser Leu Ala Pro Val Phe Pro                                           #        920                                                                   #CTCATGCTGG  2850AGAGGAA GGCAAAGGAG ACCCGAAAGG ACATCCTCAT                      #ACCTACCGGG  2910GCTGCTG CCCGCATCCG GCTGTGAACC ATCAGCTCTT                      #TTTTGTGGCT  2970CCTCAGC AGCTGCTTGG GCTTCATCTC CTCTTGTCTT                      #ACCGACCATC  3030AAGGCCA GCGGAAGCAC ACGCCTCTCA GGCTGCACTC                      #GAGATAGCTC  3090ACTTCGG CCAGGGCTCT GCAGAGGCCT CGGAACACCA                      #GAGAGCAGAG  3150CCTCCCC TCAAGTCCAG GCCTTCTAGC ACGCACCCAT                      #GCCCCAAGGC  3210ACGCCTT GAGGGTGTTC TGAGGAGGCC ACCAGTGGGA                      #ACCTGGGTCT  3270TGGACAG AAGCAAAGCT TCAGCCCTTA AGGGCTATTC                      #TCGATACCGT  3330TGGCTTC GCCCTCGTGC CGAATTCGAT ATCAAGCTTA                      #   3344                                                                       - (2) INFORMATION FOR SEQ ID NO:14:                                            -      (i) SEQUENCE CHARACTERISTICS:                                           #acids    (A) LENGTH: 921 amino                                                          (B) TYPE: amino acid                                                           (C) STRANDEDNESS: single                                                       (D) TOPOLOGY: linear                                                 -     (ii) MOLECULE TYPE: protein                                              -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:14:                                 #Arg Ser Leu Val Trp Gluer Leu Gly Arg Leu                                     #                 15                                                           #Trp Ile Pro Asp Ser Argeu Val Cys Ala Phe                                     #             30                                                               #Ile Phe Glu Tyr Ala Asple Arg Ile Gly Gly                                     #         45                                                                   #Glu His Ala Phe Arg Pheal Met Asn Ala Glu                                     #     60                                                                       #Leu Leu Pro Asn Thr Thrsn Arg Asn Arg Thr                                     # 80                                                                           #His Asp Ser Phe Glu Alaln Arg Ile His Phe                                     #                 95                                                           #Gly Val Val Ala Ile Phesp Gln Leu Ala Leu                                     #            110                                                               #Val Gln Ser Ile Cys Asner Cys Ile Asn Ala                                     #        125                                                                   #Trp Lys His His Pro Leuis Ile Gln Leu Arg                                     #    140                                                                       #Tyr Pro Asp Tyr Ala Serhe Tyr Val Asn Leu                                     #160                                                                           #Ser Leu Lys Trp Arg Sereu Asp Leu Val Gln                                     #                175                                                           #Leu Ile Arg Leu Gln Glusp Asp Ser Thr Gly                                     #            190                                                               #Arg Leu Lys Ile Arg Glner Arg Tyr Asn Ile                                     #        205                                                                   #Leu Leu Lys Glu Met Lyssp Asp Ser Arg Pro                                     #    220                                                                       #Cys Ser His Thr Met Alarg Ile Ile Phe Asp                                     #240                                                                           #Gly Met Met Thr Glu Tyrln Ala Met Ala Met                                     #                255                                                           #Tyr Ala Leu Asp Leu Gluhr Thr Leu Asp Leu                                     #            270                                                               #Gly Phe Arg Ile Leu Asnly Val Asn Leu Thr                                     #        285                                                                   #Glu Lys Trp Ser Met Glual Ser Ala Ile Val                                     #    300                                                                       #Gly Leu Leu Asp Gly Valro Arg Ala Glu Ser                                     #320                                                                           #Ala Val His Ile Val Serla Leu Leu Tyr Asp                                     #                335                                                           #Val Asn Ser Leu Gln Cysla Pro Gln Met Thr                                     #            350                                                               #Arg Phe Met Asn Phe Ilerp Arg Phe Gly Gly                                     #        365                                                                   #Arg Ile Val Phe Asn Lyslu Gly Leu Thr Gly                                     #    380                                                                       #Asp Ile Ile Ser Leu Lyshr Asp Phe Asp Leu                                     #400                                                                           #Ser Pro Ala Asp Gly Leuys Val Gly Val Trp                                     #                415                                                           #Pro Asn Val Thr Asp Serla Lys Gly Arg Gly                                     #            430                                                               #Leu Leu Glu Glu Pro Pheeu Ile Val Thr Thr                                     #        445                                                                   #Tyr Gly Asn Asp Arg Pheer Asp Arg Thr Leu                                     #    460                                                                       #Leu Ala His Ile Leu Glysp Leu Leu Lys Glu                                     #480                                                                           #Gly Lys Tyr Gly Ala Glnrg Leu Val Glu Asp                                     #                495                                                           #Lys Glu Leu Ile Asp Hisrp Asn Gly Met Val                                     #            510                                                               #Ile Thr His Val Arg Glual Ala Pro Leu Thr                                     #        525                                                                   #Thr Leu Gly Val Ser Ileer Lys Pro Phe Met                                     #    540                                                                       #Ser Val Phe Ser Phe Leusn Gly Thr Asn Pro                                     #560                                                                           #Val Leu Leu Ala Tyr Leusp Ile Trp Met Tyr                                     #                575                                                           #Arg Phe Ser Pro Tyr Glueu Phe Val Ile Ala                                     #            590                                                               #Ser Glu Val Val Glu Asnro Cys Asn Pro Gly                                     #        605                                                                   #Gly Met Gly Ser Leu Metsn Ser Phe Trp Phe                                     #    620                                                                       #Leu Ser Thr Arg Ile Ileeu Met Pro Lys Ala                                     #640                                                                           #Ile Ile Ser Ser Tyr Thrhe Phe Thr Leu Ile                                     #                655                                                           #Arg Met Glu Ser Pro Ilehe Leu Thr Val Glu                                     #            670                                                               #Lys Ile Glu Tyr Gly Alaeu Ala Lys Gln Thr                                     #        685                                                                   #Lys Lys Ser Lys Ile Serhr Met Thr Phe Phe                                     #    700                                                                       #Ser Lys Pro Ser Ala Leurp Ala Phe Met Ser                                     #720                                                                           #Thr Leu Thr Ala Asp Tyrlu Gly Ile Gln Arg                                     #                735                                                           #Tyr Ile Thr Gln Arg Asner Thr Thr Ile Glu                                     #            750                                                               #Asp Ser Lys Gly Tyr Glyle Gly Gly Leu Ile                                     #        765                                                                   #Asp Lys Ile Thr Ile Alaly Ser Pro Tyr Arg                                     #    780                                                                       #His Ile Met Lys Glu Lyslu Glu Asp Lys Leu                                     #800                                                                           #Glu Asn Lys Glu Ala Serly Cys Pro Glu Glu                                     #                815                                                           #Phe Ile Val Leu Ala Alays Ile Gly Gly Ile                                     #            830                                                               #Gly Glu Phe Ile Tyr Lysal Leu Val Ala Val                                     #        845                                                                   #Ser Phe Cys Ser Thr Vallu Arg Glu Gln Arg                                     #    860                                                                       #Gln Arg Arg Leu Lys Hishe Ser Leu Thr Cys                                     #880                                                                           #Asp Ala Val Ile Asn Metet Met Val Lys Thr                                     #                895                                                           #Lys Asp Ser Met Ser Cysrg Arg Leu Pro Gly                                     #            910                                                               -  Ser Thr Ser Leu Ala Pro Val Phe Pro                                         #        920                                                                   __________________________________________________________________________ 

What is claimed is:
 1. A substantially pure polypeptide, wherein said polypeptide comprises the amino acid sequence of GluR1 (Sequence ID No. 2), GluR2 (Sequence ID No. 4), GluR3 (Sequence ID No. 6), GluR4 (Sequence ID No. 8), GluR5 (Sequence ID No. 10), GluR6 (Sequence ID No. 12), or GluR7 (Sequence ID No. 14), and immunologically reactive fragments thereof.
 2. A polypeptide according to claim 1, said immunologically reactive fragements comprising at least 15 contiguous amino acids of GluR1 (Sequence ID No. 2), GluR2 (Sequence ID No. 4), GluR3 (Sequence ID No. 6), GluR4 (Sequence ID No. 8), GluR5 (Sequence ID No. 10), GluR6 (Sequence ID No. 12), or GluR7 (Sequence ID No. 14).
 3. A composition comprising a recombinant homomeric receptor formed of any one of the polypeptides GluR1 (Sequence ID No. 2), GluR2 (Sequence ID No. 4), GluR3 (Sequence ID No. 6), GluR4 (Sequence ID No. 8), GluR5 (Sequence ID No. 10), GluR6 (Sequence ID No. 12), or GluR7 (Sequence ID No, 14).
 4. A composition comprising a recombinant heteromeric receptor formed of any two or more of the polypeptides GluR1 (Sequence ID No. 2), GluR2 (Sequence ID No. 4), GluR3 (Sequence ID No. 6), GluR4 (Sequence ID No. 8), GluR5 (Sequence ID No. 10), GluR6 (Sequence ID No. 12), or GluR7 (Sequence ID No. 14).
 5. A substantially pure mammalian polypeptide, wherein said polypeptide is encoded by a cDNA which hybridizes under low stringency conditions to the complement of a nucleic acid having a nucleotide sequence selected from the group consisting of SEQ ID NO:1, SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 and SEQ ID NO:
 13. 6. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:1.
 7. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:3.
 8. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:5.
 9. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:7.
 10. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:9.
 11. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:11.
 12. A substantially pure mammalian polypeptide according to claim 5 wherein said nucleotide sequence is SEQ ID NO:13. 